diff --git a/src/libslic3r/PerimeterGenerator.cpp b/src/libslic3r/PerimeterGenerator.cpp
index 51c26209e..01d3c592a 100644
--- a/src/libslic3r/PerimeterGenerator.cpp
+++ b/src/libslic3r/PerimeterGenerator.cpp
@@ -8,7 +8,7 @@
 
 namespace Slic3r {
 
-static ExtrusionPaths thick_polyline_to_extrusion_paths(const ThickPolyline &thick_polyline, ExtrusionRole role, const Flow &flow, const float tolerance)
+static ExtrusionPaths thick_polyline_to_extrusion_paths(const ThickPolyline &thick_polyline, ExtrusionRole role, const Flow &flow, const float tolerance, const float merge_tolerance)
 {
     ExtrusionPaths paths;
     ExtrusionPath path(role);
@@ -71,7 +71,7 @@ static ExtrusionPaths thick_polyline_to_extrusion_paths(const ThickPolyline &thi
             path.height      = new_flow.height();
         } else {
             thickness_delta = fabs(scale_(flow.width()) - w);
-            if (thickness_delta <= tolerance) {
+            if (thickness_delta <= merge_tolerance) {
                 // the width difference between this line and the current flow width is 
                 // within the accepted tolerance
                 path.polyline.append(line.b);
@@ -95,7 +95,7 @@ static void variable_width(const ThickPolylines& polylines, ExtrusionRole role,
 	// of segments, and any pruning shall be performed before we apply this tolerance.
 	const float tolerance = float(scale_(0.05));
 	for (const ThickPolyline &p : polylines) {
-		ExtrusionPaths paths = thick_polyline_to_extrusion_paths(p, role, flow, tolerance);
+		ExtrusionPaths paths = thick_polyline_to_extrusion_paths(p, role, flow, tolerance, tolerance);
 		// Append paths to collection.
 		if (! paths.empty()) {
 			if (paths.front().first_point() == paths.back().last_point())
diff --git a/src/slic3r/CMakeLists.txt b/src/slic3r/CMakeLists.txt
index d6bd8118e..835980c60 100644
--- a/src/slic3r/CMakeLists.txt
+++ b/src/slic3r/CMakeLists.txt
@@ -225,6 +225,8 @@ set(SLIC3R_GUI_SOURCES
     GUI/DesktopIntegrationDialog.hpp
     GUI/HintNotification.cpp
     GUI/HintNotification.hpp
+    Utils/AppUpdater.cpp
+    Utils/AppUpdater.hpp
     Utils/Http.cpp
     Utils/Http.hpp
     Utils/FixModelByWin10.cpp
@@ -272,6 +274,7 @@ if (APPLE)
     list(APPEND SLIC3R_GUI_SOURCES
             Utils/RetinaHelperImpl.mm
             Utils/MacDarkMode.mm
+            Utils/MacUtils.mm
             GUI/RemovableDriveManagerMM.mm
             GUI/RemovableDriveManagerMM.h
             GUI/Mouse3DHandlerMac.mm
diff --git a/src/slic3r/GUI/Camera.cpp b/src/slic3r/GUI/Camera.cpp
index 77ce27a79..1370484c3 100644
--- a/src/slic3r/GUI/Camera.cpp
+++ b/src/slic3r/GUI/Camera.cpp
@@ -106,7 +106,11 @@ double Camera::get_fov() const
 void Camera::apply_viewport(int x, int y, unsigned int w, unsigned int h)
 {
     glsafe(::glViewport(0, 0, w, h));
+#if ENABLE_LEGACY_OPENGL_REMOVAL
+    m_viewport = { 0, 0, int(w), int(h) };
+#else
     glsafe(::glGetIntegerv(GL_VIEWPORT, m_viewport.data()));
+#endif // ENABLE_LEGACY_OPENGL_REMOVAL
 }
 
 #if !ENABLE_LEGACY_OPENGL_REMOVAL
diff --git a/src/slic3r/GUI/GLCanvas3D.cpp b/src/slic3r/GUI/GLCanvas3D.cpp
index 5c40712bc..61ef0670a 100644
--- a/src/slic3r/GUI/GLCanvas3D.cpp
+++ b/src/slic3r/GUI/GLCanvas3D.cpp
@@ -3438,6 +3438,7 @@ void GLCanvas3D::on_mouse(wxMouseEvent& evt)
 #endif // !ENABLE_NEW_RECTANGLE_SELECTION
         else {
 #if ENABLE_NEW_RECTANGLE_SELECTION
+            const bool rectangle_selection_dragging = m_rectangle_selection.is_dragging();
             if (evt.LeftDown() && (evt.ShiftDown() || evt.AltDown()) && m_picking_enabled) {
                 if (m_gizmos.get_current_type() != GLGizmosManager::SlaSupports &&
                     m_gizmos.get_current_type() != GLGizmosManager::FdmSupports &&
@@ -3454,8 +3455,7 @@ void GLCanvas3D::on_mouse(wxMouseEvent& evt)
             // during the scene manipulation.
 
 #if ENABLE_NEW_RECTANGLE_SELECTION
-            if (m_picking_enabled && (!any_gizmo_active || !evt.ShiftDown()) && (!m_hover_volume_idxs.empty() || !is_layers_editing_enabled()) &&
-                !m_rectangle_selection.is_dragging()) {
+            if (m_picking_enabled && !any_gizmo_active && (!m_hover_volume_idxs.empty() || !is_layers_editing_enabled()) && !rectangle_selection_dragging) {
 #else
             if (m_picking_enabled && (!any_gizmo_active || !evt.CmdDown()) && (!m_hover_volume_idxs.empty() || !is_layers_editing_enabled())) {
 #endif // ENABLE_NEW_RECTANGLE_SELECTION
@@ -3599,9 +3599,9 @@ void GLCanvas3D::on_mouse(wxMouseEvent& evt)
         }
         // do not process the dragging if the left mouse was set down in another canvas
 #if ENABLE_NEW_CAMERA_MOVEMENTS
-        else if (evt.LeftIsDown() || evt.MiddleIsDown()) {
+        else if (evt.LeftIsDown()) {
             // if dragging over blank area with left button, rotate
-            if ((any_gizmo_active || evt.CmdDown() || evt.MiddleIsDown() || m_hover_volume_idxs.empty()) && m_mouse.is_start_position_3D_defined()) {
+            if ((any_gizmo_active || evt.CmdDown() || m_hover_volume_idxs.empty()) && m_mouse.is_start_position_3D_defined()) {
 #else
             // if dragging over blank area with left button, rotate
         else if (evt.LeftIsDown()) {
@@ -3625,13 +3625,8 @@ void GLCanvas3D::on_mouse(wxMouseEvent& evt)
             }
             m_mouse.drag.start_position_3D = Vec3d((double)pos.x(), (double)pos.y(), 0.0);
         }
-#if ENABLE_NEW_CAMERA_MOVEMENTS
-        else if (evt.RightIsDown()) {
-            // If dragging with right button, pan.
-#else
         else if (evt.MiddleIsDown() || evt.RightIsDown()) {
-            // If dragging over blank area with right button, pan.
-#endif // ENABLE_NEW_CAMERA_MOVEMENTS
+            // If dragging over blank area with right/middle button, pan.
             if (m_mouse.is_start_position_2D_defined()) {
                 // get point in model space at Z = 0
                 float z = 0.0f;
@@ -6078,35 +6073,34 @@ void GLCanvas3D::_render_camera_target()
 
 #if ENABLE_LEGACY_OPENGL_REMOVAL
     const Vec3f& target = wxGetApp().plater()->get_camera().get_target().cast<float>();
-    bool target_changed = !m_camera_target.target.isApprox(target.cast<double>());
     m_camera_target.target = target.cast<double>();
 
     for (int i = 0; i < 3; ++i) {
-        if (!m_camera_target.axis[i].is_initialized() || target_changed) {
+        if (!m_camera_target.axis[i].is_initialized()) {
             m_camera_target.axis[i].reset();
 
             GLModel::Geometry init_data;
-            init_data.format = { GLModel::Geometry::EPrimitiveType::Lines, GLModel::Geometry::EVertexLayout::P3, GLModel::Geometry::EIndexType::USHORT };
+            init_data.format = { GLModel::Geometry::EPrimitiveType::Lines, GLModel::Geometry::EVertexLayout::P3 };
             init_data.color = (i == X) ? ColorRGBA::X() : ((i == Y) ? ColorRGBA::Y() : ColorRGBA::Z());
             init_data.reserve_vertices(2);
             init_data.reserve_indices(2);
 
             // vertices
             if (i == X) {
-                init_data.add_vertex(Vec3f(target.x() - half_length, target.y(), target.z()));
-                init_data.add_vertex(Vec3f(target.x() + half_length, target.y(), target.z()));
+                init_data.add_vertex(Vec3f(-half_length, 0.0f, 0.0f));
+                init_data.add_vertex(Vec3f(+half_length, 0.0f, 0.0f));
             }
             else if (i == Y) {
-                init_data.add_vertex(Vec3f(target.x(), target.y() - half_length, target.z()));
-                init_data.add_vertex(Vec3f(target.x(), target.y() + half_length, target.z()));
+                init_data.add_vertex(Vec3f(0.0f, -half_length, 0.0f));
+                init_data.add_vertex(Vec3f(0.0f, +half_length, 0.0f));
             }
             else {
-                init_data.add_vertex(Vec3f(target.x(), target.y(), target.z() - half_length));
-                init_data.add_vertex(Vec3f(target.x(), target.y(), target.z() + half_length));
+                init_data.add_vertex(Vec3f(0.0f, 0.0f, -half_length));
+                init_data.add_vertex(Vec3f(0.0f, 0.0f, +half_length));
             }
 
             // indices
-            init_data.add_ushort_line(0, 1);
+            init_data.add_line(0, 1);
 
             m_camera_target.axis[i].init_from(std::move(init_data));
         }
@@ -6117,7 +6111,7 @@ void GLCanvas3D::_render_camera_target()
         shader->start_using();
 #if ENABLE_GL_SHADERS_ATTRIBUTES
         const Camera& camera = wxGetApp().plater()->get_camera();
-        shader->set_uniform("view_model_matrix", camera.get_view_matrix());
+        shader->set_uniform("view_model_matrix", camera.get_view_matrix() * Geometry::assemble_transform(m_camera_target.target));
         shader->set_uniform("projection_matrix", camera.get_projection_matrix());
 #endif // ENABLE_GL_SHADERS_ATTRIBUTES
         for (int i = 0; i < 3; ++i) {
diff --git a/src/slic3r/GUI/GLModel.cpp b/src/slic3r/GUI/GLModel.cpp
index 9c9d69526..75998609b 100644
--- a/src/slic3r/GUI/GLModel.cpp
+++ b/src/slic3r/GUI/GLModel.cpp
@@ -1130,6 +1130,7 @@ bool GLModel::send_to_gpu()
         glsafe(::glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0));
     }
     else {
+        data.index_type = Geometry::EIndexType::UINT;
         glsafe(::glBufferData(GL_ELEMENT_ARRAY_BUFFER, data.indices_size_bytes(), data.indices.data(), GL_STATIC_DRAW));
         glsafe(::glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0));
     }
diff --git a/src/slic3r/GUI/GUI.cpp b/src/slic3r/GUI/GUI.cpp
index a0b674e27..72b828307 100644
--- a/src/slic3r/GUI/GUI.cpp
+++ b/src/slic3r/GUI/GUI.cpp
@@ -10,6 +10,7 @@
 #include <boost/algorithm/string.hpp>
 #include <boost/algorithm/string/predicate.hpp>
 #include <boost/any.hpp>
+#include <boost/filesystem.hpp>
 
 #if __APPLE__
 #import <IOKit/pwr_mgt/IOPMLib.h>
@@ -476,50 +477,135 @@ void about()
 
 void desktop_open_datadir_folder()
 {
+	boost::filesystem::path path(data_dir());
+	desktop_open_folder(std::move(path));
+}
+
+void desktop_open_folder(const boost::filesystem::path& path)
+{
+	if (!boost::filesystem::is_directory(path)) 
+		return;
+
 	// Execute command to open a file explorer, platform dependent.
-	// FIXME: The const_casts aren't needed in wxWidgets 3.1, remove them when we upgrade.
-
-	const auto path = data_dir();
 #ifdef _WIN32
-		const wxString widepath = from_u8(path);
-		const wchar_t *argv[] = { L"explorer", widepath.GetData(), nullptr };
-		::wxExecute(const_cast<wchar_t**>(argv), wxEXEC_ASYNC, nullptr);
+	const wxString widepath = path.wstring();
+	const wchar_t* argv[] = { L"explorer", widepath.GetData(), nullptr };
+	::wxExecute(const_cast<wchar_t**>(argv), wxEXEC_ASYNC, nullptr);
 #elif __APPLE__
-		const char *argv[] = { "open", path.data(), nullptr };
-		::wxExecute(const_cast<char**>(argv), wxEXEC_ASYNC, nullptr);
+	const char* argv[] = { "open", path.string().c_str(), nullptr };
+	::wxExecute(const_cast<char**>(argv), wxEXEC_ASYNC, nullptr);
 #else
-		const char *argv[] = { "xdg-open", path.data(), nullptr };
-
-		// Check if we're running in an AppImage container, if so, we need to remove AppImage's env vars,
-		// because they may mess up the environment expected by the file manager.
-		// Mostly this is about LD_LIBRARY_PATH, but we remove a few more too for good measure.
-		if (wxGetEnv("APPIMAGE", nullptr)) {
-			// We're running from AppImage
-			wxEnvVariableHashMap env_vars;
-			wxGetEnvMap(&env_vars);
-
-			env_vars.erase("APPIMAGE");
-			env_vars.erase("APPDIR");
-			env_vars.erase("LD_LIBRARY_PATH");
-			env_vars.erase("LD_PRELOAD");
-			env_vars.erase("UNION_PRELOAD");
-
-			wxExecuteEnv exec_env;
-			exec_env.env = std::move(env_vars);
-
-			wxString owd;
-			if (wxGetEnv("OWD", &owd)) {
-				// This is the original work directory from which the AppImage image was run,
-				// set it as CWD for the child process:
-				exec_env.cwd = std::move(owd);
-			}
-
-			::wxExecute(const_cast<char**>(argv), wxEXEC_ASYNC, nullptr, &exec_env);
-		} else {
-			// Looks like we're NOT running from AppImage, we'll make no changes to the environment.
-			::wxExecute(const_cast<char**>(argv), wxEXEC_ASYNC, nullptr, nullptr);
-		}
+	const char* argv[] = { "xdg-open", path.string().c_str(), nullptr };
+	desktop_execute(argv);
 #endif
 }
 
-} }
+#ifdef __linux__
+namespace {
+wxExecuteEnv get_appimage_exec_env()
+{
+	// If we're running in an AppImage container, we need to remove AppImage's env vars,
+	// because they may mess up the environment expected by the file manager.
+	// Mostly this is about LD_LIBRARY_PATH, but we remove a few more too for good measure.
+	wxEnvVariableHashMap env_vars;
+	wxGetEnvMap(&env_vars);
+
+	env_vars.erase("APPIMAGE");
+	env_vars.erase("APPDIR");
+	env_vars.erase("LD_LIBRARY_PATH");
+	env_vars.erase("LD_PRELOAD");
+	env_vars.erase("UNION_PRELOAD");
+
+	wxExecuteEnv exec_env;
+	exec_env.env = std::move(env_vars);
+
+	wxString owd;
+	if (wxGetEnv("OWD", &owd)) {
+		// This is the original work directory from which the AppImage image was run,
+		// set it as CWD for the child process:
+		exec_env.cwd = std::move(owd);
+	}
+	return exec_env;
+}
+} // namespace
+void desktop_execute(const char* argv[])
+{
+	if (sizeof(argv) == 0)
+		return;
+
+	// Check if we're running in an AppImage container, if so, we need to remove AppImage's env vars,
+	// because they may mess up the environment expected by the file manager.
+	// Mostly this is about LD_LIBRARY_PATH, but we remove a few more too for good measure.
+	if (wxGetEnv("APPIMAGE", nullptr)) {
+		// We're running from AppImage
+		wxExecuteEnv exec_env = get_appimage_exec_env();
+		::wxExecute(const_cast<char**>(argv), wxEXEC_ASYNC, nullptr, &exec_env);
+	}
+	else {
+		// Looks like we're NOT running from AppImage, we'll make no changes to the environment.
+		::wxExecute(const_cast<char**>(argv), wxEXEC_ASYNC, nullptr, nullptr);
+	}
+}
+void desktop_execute_get_result(wxString command, wxArrayString& output)
+{
+	output.Clear();
+   //Check if we're running in an AppImage container, if so, we need to remove AppImage's env vars,
+   // because they may mess up the environment expected by the file manager.
+   // Mostly this is about LD_LIBRARY_PATH, but we remove a few more too for good measure.
+	if (wxGetEnv("APPIMAGE", nullptr)) {
+		// We're running from AppImage
+		wxExecuteEnv exec_env = get_appimage_exec_env();
+		::wxExecute(command, output, 0, &exec_env);
+	} else {
+		// Looks like we're NOT running from AppImage, we'll make no changes to the environment.
+		::wxExecute(command, output);
+	}
+}
+#endif // __linux__
+
+#ifdef _WIN32
+bool create_process(const boost::filesystem::path& path, const std::wstring& cmd_opt, std::string& error_msg)
+{
+	// find updater exe
+	if (boost::filesystem::exists(path)) {
+		// Using quoted string as mentioned in CreateProcessW docs.
+		std::wstring wcmd = L"\"" + path.wstring() + L"\"";
+		if (!cmd_opt.empty())
+			wcmd += L" " + cmd_opt;
+
+		// additional information
+		STARTUPINFOW si;
+		PROCESS_INFORMATION pi;
+
+		// set the size of the structures
+		ZeroMemory(&si, sizeof(si));
+		si.cb = sizeof(si);
+		ZeroMemory(&pi, sizeof(pi));
+
+		// start the program up
+		if (CreateProcessW(NULL,   // the path
+			wcmd.data(),    // Command line
+			NULL,           // Process handle not inheritable
+			NULL,           // Thread handle not inheritable
+			FALSE,          // Set handle inheritance to FALSE
+			0,              // No creation flags
+			NULL,           // Use parent's environment block
+			NULL,           // Use parent's starting directory 
+			&si,            // Pointer to STARTUPINFO structure
+			&pi             // Pointer to PROCESS_INFORMATION structure (removed extra parentheses)
+		)) {
+			// Close process and thread handles.
+			CloseHandle(pi.hProcess);
+			CloseHandle(pi.hThread);
+			return true;
+		}
+		else
+			error_msg = "CreateProcessW failed to create process " + boost::nowide::narrow(path.wstring());
+	}
+	else
+		error_msg = "Executable doesn't exists. Path: " + boost::nowide::narrow(path.wstring());
+	return false;
+}
+#endif //_WIN32
+
+} } // namespaces GUI / Slic3r
diff --git a/src/slic3r/GUI/GUI.hpp b/src/slic3r/GUI/GUI.hpp
index 20c882878..cb7cf5487 100644
--- a/src/slic3r/GUI/GUI.hpp
+++ b/src/slic3r/GUI/GUI.hpp
@@ -13,6 +13,7 @@ class wxWindow;
 class wxMenuBar;
 class wxComboCtrl;
 class wxFileDialog;
+class wxArrayString;
 class wxTopLevelWindow;
 
 namespace Slic3r { 
@@ -80,6 +81,24 @@ boost::filesystem::path	into_path(const wxString &str);
 extern void about();
 // Ask the destop to open the datadir using the default file explorer.
 extern void desktop_open_datadir_folder();
+// Ask the destop to open the directory specified by path using the default file explorer.
+void desktop_open_folder(const boost::filesystem::path& path);
+
+#ifdef __linux__
+// Calling wxExecute on Linux with proper handling of AppImage's env vars.
+// argv example: { "xdg-open", path.c_str(), nullptr }
+void desktop_execute(const char* argv[]);
+void desktop_execute_get_result(wxString command, wxArrayString& output);
+#endif // __linux__
+
+#ifdef _WIN32
+// Call CreateProcessW to start external proccess on path
+// returns true on success
+// path should contain path to the process
+// cmd_opt can be empty or contain command line options. Example: L"/silent"
+// error_msg will contain error message if create_process return false
+bool create_process(const boost::filesystem::path& path, const std::wstring& cmd_opt, std::string& error_msg);
+#endif //_WIN32
 
 } // namespace GUI
 } // namespace Slic3r
diff --git a/src/slic3r/GUI/GUI_App.cpp b/src/slic3r/GUI/GUI_App.cpp
index 4fdfb62d9..73eeb6ab5 100644
--- a/src/slic3r/GUI/GUI_App.cpp
+++ b/src/slic3r/GUI/GUI_App.cpp
@@ -57,6 +57,7 @@
 #include "../Utils/PrintHost.hpp"
 #include "../Utils/Process.hpp"
 #include "../Utils/MacDarkMode.hpp"
+#include "../Utils/AppUpdater.hpp"
 #include "slic3r/Config/Snapshot.hpp"
 #include "ConfigSnapshotDialog.hpp"
 #include "FirmwareDialog.hpp"
@@ -430,50 +431,21 @@ bool static check_old_linux_datadir(const wxString& app_name) {
 }
 #endif
 
-
 #ifdef _WIN32
+#if 0 // External Updater is replaced with AppUpdater.cpp
 static bool run_updater_win()
 {
     // find updater exe
     boost::filesystem::path path_updater = boost::dll::program_location().parent_path() / "prusaslicer-updater.exe";
-    if (boost::filesystem::exists(path_updater)) {
-        // run updater. Original args: /silent -restartapp prusa-slicer.exe -startappfirst
-
-        // Using quoted string as mentioned in CreateProcessW docs, silent execution parameter.
-        std::wstring wcmd = L"\"" + path_updater.wstring() + L"\" /silent";
-
-        // additional information
-        STARTUPINFOW si;
-        PROCESS_INFORMATION pi;
-
-        // set the size of the structures
-        ZeroMemory(&si, sizeof(si));
-        si.cb = sizeof(si);
-        ZeroMemory(&pi, sizeof(pi));
-
-        // start the program up
-        if (CreateProcessW(NULL,   // the path
-            wcmd.data(),    // Command line
-            NULL,           // Process handle not inheritable
-            NULL,           // Thread handle not inheritable
-            FALSE,          // Set handle inheritance to FALSE
-            0,              // No creation flags
-            NULL,           // Use parent's environment block
-            NULL,           // Use parent's starting directory 
-            &si,            // Pointer to STARTUPINFO structure
-            &pi             // Pointer to PROCESS_INFORMATION structure (removed extra parentheses)
-        )) {
-            // Close process and thread handles.
-            CloseHandle(pi.hProcess);
-            CloseHandle(pi.hThread);
-            return true;
-        } else {
-            BOOST_LOG_TRIVIAL(error) << "Failed to start prusaslicer-updater.exe with command " << wcmd;
-        }
-    }
-    return false;
+    // run updater. Original args: /silent -restartapp prusa-slicer.exe -startappfirst
+    std::string msg;
+    bool res = create_process(path_updater, L"/silent", msg);
+    if (!res)
+        BOOST_LOG_TRIVIAL(error) << msg; 
+    return res;
 }
-#endif //_WIN32
+#endif // 0
+#endif // _WIN32
 
 struct FileWildcards {
     std::string_view              title;
@@ -817,18 +789,13 @@ void GUI_App::post_init()
         CallAfter([this] {
             bool cw_showed = this->config_wizard_startup();
             this->preset_updater->sync(preset_bundle);
+            this->app_version_check(false);
             if (! cw_showed) {
                 // The CallAfter is needed as well, without it, GL extensions did not show.
                 // Also, we only want to show this when the wizard does not, so the new user
                 // sees something else than "we want something" on the first start.
                 show_send_system_info_dialog_if_needed();
             }
-        #ifdef _WIN32
-            // Run external updater on Windows if version check is enabled.
-            if (this->preset_updater->version_check_enabled() && ! run_updater_win())
-                // "prusaslicer-updater.exe" was not started, run our own update check.
-        #endif // _WIN32
-                this->preset_updater->slic3r_update_notify();
         });
     }
 
@@ -854,6 +821,8 @@ GUI_App::GUI_App(EAppMode mode)
 {
 	//app config initializes early becasuse it is used in instance checking in PrusaSlicer.cpp
 	this->init_app_config();
+    // init app downloader after path to datadir is set
+    m_app_updater = std::make_unique<AppUpdater>();
 }
 
 GUI_App::~GUI_App()
@@ -1243,23 +1212,8 @@ bool GUI_App::on_init_inner()
 #endif // __WXMSW__
 
         preset_updater = new PresetUpdater();
-        Bind(EVT_SLIC3R_VERSION_ONLINE, [this](const wxCommandEvent& evt) {
-            app_config->set("version_online", into_u8(evt.GetString()));
-            app_config->save();
-            std::string opt = app_config->get("notify_release");
-            if (this->plater_ != nullptr && (opt == "all" || opt == "release")) {
-                if (*Semver::parse(SLIC3R_VERSION) < *Semver::parse(into_u8(evt.GetString()))) {
-                    this->plater_->get_notification_manager()->push_notification(NotificationType::NewAppAvailable
-                        , NotificationManager::NotificationLevel::ImportantNotificationLevel
-                        , Slic3r::format(_u8L("New release version %1% is available."), evt.GetString())
-                        , _u8L("See Download page.")
-                        , [](wxEvtHandler* evnthndlr) {wxGetApp().open_web_page_localized("https://www.prusa3d.com/slicerweb"); return true; }
-                    );
-                }
-            }
-            });
+        Bind(EVT_SLIC3R_VERSION_ONLINE, &GUI_App::on_version_read, this);
         Bind(EVT_SLIC3R_EXPERIMENTAL_VERSION_ONLINE, [this](const wxCommandEvent& evt) {
-            app_config->save();
             if (this->plater_ != nullptr && app_config->get("notify_release") == "all") {
                 std::string evt_string = into_u8(evt.GetString());
                 if (*Semver::parse(SLIC3R_VERSION) < *Semver::parse(evt_string)) {
@@ -1273,6 +1227,22 @@ bool GUI_App::on_init_inner()
                 }
             }
             });
+        Bind(EVT_SLIC3R_APP_DOWNLOAD_PROGRESS, [this](const wxCommandEvent& evt) {
+            //lm:This does not force a render. The progress bar only updateswhen the mouse is moved.
+            if (this->plater_ != nullptr)
+                this->plater_->get_notification_manager()->set_download_progress_percentage((float)std::stoi(into_u8(evt.GetString())) / 100.f );
+        });
+
+        Bind(EVT_SLIC3R_APP_DOWNLOAD_FAILED, [this](const wxCommandEvent& evt) {
+            if (this->plater_ != nullptr)
+                this->plater_->get_notification_manager()->close_notification_of_type(NotificationType::AppDownload);
+            if(!evt.GetString().IsEmpty())
+                show_error(nullptr, evt.GetString());
+        });
+
+        Bind(EVT_SLIC3R_APP_OPEN_FAILED, [](const wxCommandEvent& evt) {
+            show_error(nullptr, evt.GetString());
+        });
     }
     else {
 #ifdef __WXMSW__ 
@@ -2283,7 +2253,8 @@ void GUI_App::add_config_menu(wxMenuBar *menu)
         local_menu->Append(config_id_base + ConfigMenuWizard, config_wizard_name + dots, config_wizard_tooltip);
         local_menu->Append(config_id_base + ConfigMenuSnapshots, _L("&Configuration Snapshots") + dots, _L("Inspect / activate configuration snapshots"));
         local_menu->Append(config_id_base + ConfigMenuTakeSnapshot, _L("Take Configuration &Snapshot"), _L("Capture a configuration snapshot"));
-        local_menu->Append(config_id_base + ConfigMenuUpdate, _L("Check for Configuration Updates"), _L("Check for configuration updates"));
+        local_menu->Append(config_id_base + ConfigMenuUpdateConf, _L("Check for Configuration Updates"), _L("Check for configuration updates"));
+        local_menu->Append(config_id_base + ConfigMenuUpdateApp, _L("Check for Application Updates"), _L("Check for new version of application"));
 #if defined(__linux__) && defined(SLIC3R_DESKTOP_INTEGRATION) 
         //if (DesktopIntegrationDialog::integration_possible())
         local_menu->Append(config_id_base + ConfigMenuDesktopIntegration, _L("Desktop Integration"), _L("Desktop Integration"));    
@@ -2325,9 +2296,12 @@ void GUI_App::add_config_menu(wxMenuBar *menu)
         case ConfigMenuWizard:
             run_wizard(ConfigWizard::RR_USER);
             break;
-		case ConfigMenuUpdate:
+		case ConfigMenuUpdateConf:
 			check_updates(true);
 			break;
+        case ConfigMenuUpdateApp:
+            app_version_check(true);
+            break;
 #ifdef __linux__
         case ConfigMenuDesktopIntegration:
             show_desktop_integration_dialog();
@@ -3267,5 +3241,87 @@ void GUI_App::associate_gcode_files()
 }
 #endif // __WXMSW__
 
+
+void GUI_App::on_version_read(wxCommandEvent& evt)
+{
+    app_config->set("version_online", into_u8(evt.GetString()));
+    app_config->save();
+    std::string opt = app_config->get("notify_release");
+    if (this->plater_ == nullptr || (opt != "all" && opt != "release")) {
+        return;
+    }
+    if (*Semver::parse(SLIC3R_VERSION) >= *Semver::parse(into_u8(evt.GetString()))) {
+        return;
+    }
+    // notification
+    /*
+    this->plater_->get_notification_manager()->push_notification(NotificationType::NewAppAvailable
+        , NotificationManager::NotificationLevel::ImportantNotificationLevel
+        , Slic3r::format(_u8L("New release version %1% is available."), evt.GetString())
+        , _u8L("See Download page.")
+        , [](wxEvtHandler* evnthndlr) {wxGetApp().open_web_page_localized("https://www.prusa3d.com/slicerweb"); return true; }
+    );
+    */
+    // updater 
+    // read triggered_by_user that was set when calling  GUI_App::app_version_check
+    app_updater(m_app_updater->get_triggered_by_user());
+}
+
+void GUI_App::app_updater(bool from_user)
+{
+    DownloadAppData app_data = m_app_updater->get_app_data();
+
+    if (from_user && (!app_data.version || *app_data.version <= *Semver::parse(SLIC3R_VERSION)))
+    {
+        BOOST_LOG_TRIVIAL(info) << "There is no newer version online.";
+        MsgNoAppUpdates no_update_dialog;
+        no_update_dialog.ShowModal();
+        return;
+
+    }
+
+    assert(!app_data.url.empty());
+    assert(!app_data.target_path.empty());
+
+    // dialog with new version info
+    AppUpdateAvailableDialog dialog(*Semver::parse(SLIC3R_VERSION), *app_data.version);
+    auto dialog_result = dialog.ShowModal();
+    // checkbox "do not show again"
+    if (dialog.disable_version_check()) {
+        app_config->set("notify_release", "none");
+    }
+    // Doesn't wish to update
+    if (dialog_result != wxID_OK) {
+        return;
+    }
+    // dialog with new version download (installer or app dependent on system) including path selection
+    AppUpdateDownloadDialog dwnld_dlg(*app_data.version, app_data.target_path);
+    dialog_result = dwnld_dlg.ShowModal();
+    //  Doesn't wish to download
+    if (dialog_result != wxID_OK) {
+        return;
+    }
+    app_data.target_path =dwnld_dlg.get_download_path();
+
+    // start download
+    this->plater_->get_notification_manager()->push_download_progress_notification(_utf8("Download"), std::bind(&AppUpdater::cancel_callback, this->m_app_updater.get()));
+    app_data.start_after = dwnld_dlg.run_after_download();
+    m_app_updater->set_app_data(std::move(app_data));
+    m_app_updater->sync_download();
+}
+
+void GUI_App::app_version_check(bool from_user)
+{
+    if (from_user) {
+        if (m_app_updater->get_download_ongoing()) {
+            MessageDialog msgdlg(nullptr, _L("Download of new version is already ongoing. Do you wish to continue?"), _L("Notice"), wxYES_NO);
+            if (msgdlg.ShowModal() != wxID_YES)
+                return;
+        }
+    }
+    std::string version_check_url = app_config->version_check_url();
+    m_app_updater->sync_version(version_check_url, from_user);
+}
+
 } // GUI
 } //Slic3r
diff --git a/src/slic3r/GUI/GUI_App.hpp b/src/slic3r/GUI/GUI_App.hpp
index f8ecbf630..7ff4dbefc 100644
--- a/src/slic3r/GUI/GUI_App.hpp
+++ b/src/slic3r/GUI/GUI_App.hpp
@@ -32,6 +32,7 @@ class PresetUpdater;
 class ModelObject;
 class PrintHostJobQueue;
 class Model;
+class AppUpdater;
 
 namespace GUI{
 
@@ -82,7 +83,8 @@ enum ConfigMenuIDs {
     ConfigMenuWizard,
     ConfigMenuSnapshots,
     ConfigMenuTakeSnapshot,
-    ConfigMenuUpdate,
+    ConfigMenuUpdateConf,
+    ConfigMenuUpdateApp,
     ConfigMenuDesktopIntegration,
     ConfigMenuPreferences,
     ConfigMenuModeSimple,
@@ -157,6 +159,7 @@ private:
     std::unique_ptr<ImGuiWrapper> m_imgui;
     std::unique_ptr<PrintHostJobQueue> m_printhost_job_queue;
 	std::unique_ptr <OtherInstanceMessageHandler> m_other_instance_message_handler;
+    std::unique_ptr <AppUpdater> m_app_updater;
     std::unique_ptr <wxSingleInstanceChecker> m_single_instance_checker;
     std::string m_instance_hash_string;
 	size_t m_instance_hash_int;
@@ -361,6 +364,11 @@ private:
     // Returns true if the configuration is fine. 
     // Returns true if the configuration is not compatible and the user decided to rather close the slicer instead of reconfiguring.
 	bool            check_updates(const bool verbose);
+    void            on_version_read(wxCommandEvent& evt);
+    // if the data from version file are already downloaded, shows dialogs to start download of new version of app
+    void            app_updater(bool from_user);
+    // inititate read of version file online in separate thread
+    void            app_version_check(bool from_user);
 
     bool            m_datadir_redefined { false }; 
 };
diff --git a/src/slic3r/GUI/NotificationManager.cpp b/src/slic3r/GUI/NotificationManager.cpp
index 8c80dcf7b..405c493bb 100644
--- a/src/slic3r/GUI/NotificationManager.cpp
+++ b/src/slic3r/GUI/NotificationManager.cpp
@@ -825,6 +825,120 @@ void NotificationManager::ProgressBarNotification::render_bar(ImGuiWrapper& imgu
 		imgui.text(text.c_str());
 	}
 }
+//------ProgressBarWithCancelNotification----------------
+
+void NotificationManager::ProgressBarWithCancelNotification::render_close_button(ImGuiWrapper& imgui, const float win_size_x, const float win_size_y, const float win_pos_x, const float win_pos_y)
+{
+	if (m_percentage < 0.f || m_percentage >= 1.f)
+		render_close_button_inner(imgui, win_size_x, win_size_y, win_pos_x, win_pos_y);
+	else
+		render_cancel_button_inner(imgui, win_size_x, win_size_y, win_pos_x, win_pos_y);
+}
+void NotificationManager::ProgressBarWithCancelNotification::render_close_button_inner(ImGuiWrapper& imgui, const float win_size_x, const float win_size_y, const float win_pos_x, const float win_pos_y)
+{
+	ImVec2 win_size(win_size_x, win_size_y);
+	ImVec2 win_pos(win_pos_x, win_pos_y);
+	ImGui::PushStyleColor(ImGuiCol_Button, ImVec4(.0f, .0f, .0f, .0f));
+	ImGui::PushStyleColor(ImGuiCol_ButtonHovered, ImVec4(.0f, .0f, .0f, .0f));
+	push_style_color(ImGuiCol_Text, ImVec4(1.f, 1.f, 1.f, 1.f), m_state == EState::FadingOut, m_current_fade_opacity);
+	push_style_color(ImGuiCol_TextSelectedBg, ImVec4(0, .75f, .75f, 1.f), m_state == EState::FadingOut, m_current_fade_opacity);
+	ImGui::PushStyleColor(ImGuiCol_ButtonActive, ImVec4(.0f, .0f, .0f, .0f));
+
+
+	std::string button_text;
+	button_text = ImGui::CloseNotifButton;
+
+	if (ImGui::IsMouseHoveringRect(ImVec2(win_pos.x - win_size.x / 10.f, win_pos.y),
+		ImVec2(win_pos.x, win_pos.y + win_size.y - (m_minimize_b_visible ? 2 * m_line_height : 0)),
+		true))
+	{
+		button_text = ImGui::CloseNotifHoverButton;
+	}
+	ImVec2 button_pic_size = ImGui::CalcTextSize(button_text.c_str());
+	ImVec2 button_size(button_pic_size.x * 1.25f, button_pic_size.y * 1.25f);
+	ImGui::SetCursorPosX(win_size.x - m_line_height * 2.75f);
+	ImGui::SetCursorPosY(win_size.y / 2 - button_size.y);
+	if (imgui.button(button_text.c_str(), button_size.x, button_size.y))
+	{
+		close();
+	}
+
+	//invisible large button
+	ImGui::SetCursorPosX(win_size.x - m_line_height * 2.35f);
+	ImGui::SetCursorPosY(0);
+	if (imgui.button(" ", m_line_height * 2.125, win_size.y - (m_minimize_b_visible ? 2 * m_line_height : 0)))
+	{
+		close();
+	}
+	ImGui::PopStyleColor(5);
+
+}
+
+void NotificationManager::ProgressBarWithCancelNotification::render_cancel_button_inner(ImGuiWrapper& imgui, const float win_size_x, const float win_size_y, const float win_pos_x, const float win_pos_y)
+{
+	ImVec2 win_size(win_size_x, win_size_y);
+	ImVec2 win_pos(win_pos_x, win_pos_y);
+	ImGui::PushStyleColor(ImGuiCol_Button, ImVec4(.0f, .0f, .0f, .0f));
+	ImGui::PushStyleColor(ImGuiCol_ButtonHovered, ImVec4(.0f, .0f, .0f, .0f));
+	push_style_color(ImGuiCol_Text, ImVec4(1.f, 1.f, 1.f, 1.f), m_state == EState::FadingOut, m_current_fade_opacity);
+	push_style_color(ImGuiCol_TextSelectedBg, ImVec4(0, .75f, .75f, 1.f), m_state == EState::FadingOut, m_current_fade_opacity);
+	ImGui::PushStyleColor(ImGuiCol_ButtonActive, ImVec4(.0f, .0f, .0f, .0f));
+
+
+	std::string button_text;
+	button_text = ImGui::CancelButton;
+
+	if (ImGui::IsMouseHoveringRect(ImVec2(win_pos.x - win_size.x / 10.f, win_pos.y),
+		ImVec2(win_pos.x, win_pos.y + win_size.y - (m_minimize_b_visible ? 2 * m_line_height : 0)),
+		true))
+	{
+		button_text = ImGui::CancelHoverButton;
+	}
+	ImVec2 button_pic_size = ImGui::CalcTextSize(button_text.c_str());
+	ImVec2 button_size(button_pic_size.x * 1.25f, button_pic_size.y * 1.25f);
+	ImGui::SetCursorPosX(win_size.x - m_line_height * 2.75f);
+	ImGui::SetCursorPosY(win_size.y / 2 - button_size.y);
+	if (imgui.button(button_text.c_str(), button_size.x, button_size.y))
+	{
+		on_cancel_button();
+	}
+
+	//invisible large button
+	ImGui::SetCursorPosX(win_size.x - m_line_height * 2.35f);
+	ImGui::SetCursorPosY(0);
+	if (imgui.button(" ", m_line_height * 2.125, win_size.y - (m_minimize_b_visible ? 2 * m_line_height : 0)))
+	{
+		on_cancel_button();
+	}
+	ImGui::PopStyleColor(5);
+
+}
+
+void NotificationManager::ProgressBarWithCancelNotification::on_cancel_button()
+{
+	if (m_cancel_callback) {
+		if (m_cancel_callback()) {
+			close();
+		}
+	}
+}
+
+void NotificationManager::ProgressBarWithCancelNotification::render_bar(ImGuiWrapper& imgui, const float win_size_x, const float win_size_y, const float win_pos_x, const float win_pos_y)
+{
+	ProgressBarNotification::render_bar(imgui, win_size_x, win_size_y, win_pos_x, win_pos_y);
+	std::string text;
+	if (m_percentage < 0.f) {
+		text = _u8L("ERROR");
+	} else {
+		std::stringstream stream;
+		stream << std::fixed << std::setprecision(2) << (int)(m_percentage * 100) << "%";
+		text = stream.str();
+	}
+	ImGui::SetCursorPosX(m_left_indentation);
+	ImGui::SetCursorPosY(win_size_y / 2 + win_size_y / 6 - (m_multiline ? 0 : m_line_height / 4));
+	imgui.text(text.c_str());
+}
+
 //------PrintHostUploadNotification----------------
 void NotificationManager::PrintHostUploadNotification::init()
 {
@@ -1659,11 +1773,42 @@ void NotificationManager::upload_job_notification_show_error(int id, const std::
 	}
 }
 
+void NotificationManager::push_download_progress_notification(const std::string& text, std::function<bool()> cancel_callback)
+{
+	// If already exists, change text and reset progress
+	for (std::unique_ptr<PopNotification>& notification : m_pop_notifications) {
+		if (notification->get_type() == NotificationType::AppDownload) {
+			notification->update({ NotificationType::AppDownload, NotificationLevel::ProgressBarNotificationLevel, 10, text });
+			auto* pbwcn = dynamic_cast<ProgressBarWithCancelNotification*>(notification.get());
+			pbwcn->set_percentage(0.0f);
+			pbwcn->set_cancel_callback(cancel_callback);
+			return;
+		}
+	}
+	// push new one
+	NotificationData data{ NotificationType::AppDownload, NotificationLevel::ProgressBarNotificationLevel, 10, text };
+	push_notification_data(std::make_unique<NotificationManager::ProgressBarWithCancelNotification>(data, m_id_provider, m_evt_handler, cancel_callback), 0);
+}
+void NotificationManager::set_download_progress_percentage(float percentage)
+{
+ 	for (std::unique_ptr<PopNotification>& notification : m_pop_notifications) {
+		if (notification->get_type() == NotificationType::AppDownload) {
+			ProgressBarWithCancelNotification* pbwcn = dynamic_cast<ProgressBarWithCancelNotification*>(notification.get());
+			// if this changes the percentage, it should be shown now
+			float percent_b4 = pbwcn->get_percentage();
+			pbwcn->set_percentage(percentage);
+			if (pbwcn->get_percentage() != percent_b4)
+				wxGetApp().plater()->get_current_canvas3D()->schedule_extra_frame(0);
+			return;
+		}
+	}
+}
+
 void NotificationManager::init_slicing_progress_notification(std::function<bool()> cancel_callback)
 {
 	for (std::unique_ptr<PopNotification>& notification : m_pop_notifications) {
 		if (notification->get_type() == NotificationType::SlicingProgress) {
-			dynamic_cast<SlicingProgressNotification*>(notification.get())->set_cancel_callback(cancel_callback);	
+	 		dynamic_cast<SlicingProgressNotification*>(notification.get())->set_cancel_callback(cancel_callback);	
 			return;
 		}
 	}
diff --git a/src/slic3r/GUI/NotificationManager.hpp b/src/slic3r/GUI/NotificationManager.hpp
index af1d836eb..0fd32ff8b 100644
--- a/src/slic3r/GUI/NotificationManager.hpp
+++ b/src/slic3r/GUI/NotificationManager.hpp
@@ -78,6 +78,8 @@ enum class NotificationType
 	ProgressBar,
 	// Progress bar with info from Print Host Upload Queue dialog.
 	PrintHostUpload,
+	// Progress bar of download next version app.
+	AppDownload,
 	// Progress bar with cancel button, cannot be closed
 	// On end of slicing and G-code processing (the full G-code preview is available),
 	// contains a hyperlink to export the G-code to a removable media or hdd.
@@ -205,6 +207,9 @@ public:
 	void set_upload_job_notification_percentage(int id, const std::string& filename, const std::string& host, float percentage);
 	void upload_job_notification_show_canceled(int id, const std::string& filename, const std::string& host);
 	void upload_job_notification_show_error(int id, const std::string& filename, const std::string& host);
+	// Download App progress
+	void push_download_progress_notification(const std::string& text, std::function<bool()>	cancel_callback);
+	void set_download_progress_percentage(float percentage);
 	// slicing progress
 	void init_slicing_progress_notification(std::function<bool()> cancel_callback);
 	void set_slicing_progress_began();
@@ -439,6 +444,7 @@ private:
 		
 		ProgressBarNotification(const NotificationData& n, NotificationIDProvider& id_provider, wxEvtHandler* evt_handler) : PopNotification(n, id_provider, evt_handler) { }
 		virtual void set_percentage(float percent) { m_percentage = percent; }
+		float get_percentage() const { return m_percentage; }
 	protected:
 		virtual void init() override;		
 		virtual void	render_text(ImGuiWrapper& imgui,
@@ -461,7 +467,35 @@ private:
 		
 	};
 
-	
+	class ProgressBarWithCancelNotification : public ProgressBarNotification
+	{
+	public:
+		ProgressBarWithCancelNotification(const NotificationData& n, NotificationIDProvider& id_provider, wxEvtHandler* evt_handler, std::function<bool()> cancel_callback) 
+			: ProgressBarNotification(n, id_provider, evt_handler)
+			, m_cancel_callback(cancel_callback)
+		{ 
+		}
+		void	set_percentage(float percent) override { m_percentage = percent; if(m_percentage >= 1.f) m_state = EState::FadingOut; else m_state = EState::NotFading; }
+		void	set_cancel_callback(std::function<bool()> cancel_callback) { m_cancel_callback = cancel_callback; }
+
+	protected:
+		void	render_close_button(ImGuiWrapper& imgui,
+										const float win_size_x, const float win_size_y,
+										const float win_pos_x, const float win_pos_y) override;
+		void    render_close_button_inner(ImGuiWrapper& imgui,
+											const float win_size_x, const float win_size_y,
+											const float win_pos_x, const float win_pos_y);
+		void    render_cancel_button_inner(ImGuiWrapper& imgui,
+											const float win_size_x, const float win_size_y,
+											const float win_pos_x, const float win_pos_y);
+		void	render_bar(ImGuiWrapper& imgui,
+							const float win_size_x, const float win_size_y,
+							const float win_pos_x, const float win_pos_y) override;
+		void    on_cancel_button();
+
+		std::function<bool()>	m_cancel_callback;
+		long					m_hover_time{ 0 };
+	};
 
 	class PrintHostUploadNotification : public ProgressBarNotification
 	{
diff --git a/src/slic3r/GUI/UpdateDialogs.cpp b/src/slic3r/GUI/UpdateDialogs.cpp
index f80975ce5..0441e866f 100644
--- a/src/slic3r/GUI/UpdateDialogs.cpp
+++ b/src/slic3r/GUI/UpdateDialogs.cpp
@@ -3,6 +3,7 @@
 #include <cstring>
 #include <boost/format.hpp>
 #include <boost/algorithm/string/predicate.hpp>
+#include <boost/nowide/convert.hpp>
 
 #include <wx/settings.h>
 #include <wx/sizer.h>
@@ -14,11 +15,13 @@
 
 #include "libslic3r/libslic3r.h"
 #include "libslic3r/Utils.hpp"
+#include "../Utils/AppUpdater.hpp"
 #include "GUI.hpp"
 #include "GUI_App.hpp"
 #include "I18N.hpp"
 #include "ConfigWizard.hpp"
 #include "wxExtensions.hpp"
+#include "format.hpp"
 
 namespace Slic3r {
 namespace GUI {
@@ -88,6 +91,125 @@ bool MsgUpdateSlic3r::disable_version_check() const
 	return cbox->GetValue();
 }
 
+ wxSize AppUpdateAvailableDialog::AUAD_size;
+// AppUpdater
+AppUpdateAvailableDialog::AppUpdateAvailableDialog(const Semver& ver_current, const Semver& ver_online)
+	: MsgDialog(nullptr, _(L("App Update available")), wxString::Format(_(L("New version of %s is available.\nDo you wish to download it?")), SLIC3R_APP_NAME))
+{
+	auto* versions = new wxFlexGridSizer(1, 0, VERT_SPACING);
+	versions->Add(new wxStaticText(this, wxID_ANY, _(L("Current version:"))));
+	versions->Add(new wxStaticText(this, wxID_ANY, ver_current.to_string()));
+	versions->Add(new wxStaticText(this, wxID_ANY, _(L("New version:"))));
+	versions->Add(new wxStaticText(this, wxID_ANY, ver_online.to_string()));
+	content_sizer->Add(versions);
+	content_sizer->AddSpacer(VERT_SPACING);
+
+	cbox = new wxCheckBox(this, wxID_ANY, _(L("Don't notify about new releases any more")));
+	content_sizer->Add(cbox);
+	content_sizer->AddSpacer(VERT_SPACING);
+	
+	AUAD_size = content_sizer->GetSize();
+	
+
+	add_button(wxID_CANCEL);
+
+	if (auto* btn_ok = get_button(wxID_OK); btn_ok != NULL) {
+		btn_ok->SetLabel(_L("Next"));
+	}
+
+	finalize();
+}
+
+AppUpdateAvailableDialog::~AppUpdateAvailableDialog() {}
+
+
+bool AppUpdateAvailableDialog::disable_version_check() const
+{
+	return cbox->GetValue();
+}
+
+// AppUpdateDownloadDialog
+AppUpdateDownloadDialog::AppUpdateDownloadDialog( const Semver& ver_online, boost::filesystem::path& path)
+	: MsgDialog(nullptr, _(L("App Update download")), wxString::Format(_(L("New version of %s is available.")), SLIC3R_APP_NAME))
+{
+	auto* versions = new wxFlexGridSizer(2, 0, VERT_SPACING);
+	versions->Add(new wxStaticText(this, wxID_ANY, _(L("New version:"))));
+	versions->Add(new wxStaticText(this, wxID_ANY, ver_online.to_string()));
+	content_sizer->Add(versions);
+	content_sizer->AddSpacer(VERT_SPACING);
+#ifndef __linux__
+	cbox_run = new wxCheckBox(this, wxID_ANY, _(L("Run installer after download. (Otherwise file explorer will be opened)")));
+	content_sizer->Add(cbox_run);
+#endif
+	content_sizer->AddSpacer(VERT_SPACING);
+	content_sizer->AddSpacer(VERT_SPACING);
+	content_sizer->Add(new wxStaticText(this, wxID_ANY, _(L("Target path:"))));
+	content_sizer->AddSpacer(VERT_SPACING);
+	txtctrl_path = new wxTextCtrl(this, wxID_ANY, path.wstring());
+	content_sizer->Add(txtctrl_path, 1, wxEXPAND);
+	content_sizer->AddSpacer(VERT_SPACING);
+	
+	wxButton* btn = new wxButton(this, wxID_ANY, _L("Select path"));
+	content_sizer->Add(btn/*, 1, wxEXPAND*/);
+
+	// button to open file dialog
+	btn->Bind(wxEVT_BUTTON, ([this, path](wxCommandEvent& e) {
+		std::string extension = path.filename().extension().string();
+		wxString wildcard;
+		if (!extension.empty()) {
+			extension = extension.substr(1);
+			wxString wxext = boost::nowide::widen(extension);
+			wildcard = GUI::format_wxstr("%1% Files (*.%2%)|*.%2%", wxext.Upper(), wxext);
+		}
+		wxFileDialog save_dlg(
+			this
+			, _L("Save as:")
+			, txtctrl_path->GetValue()
+			, boost::nowide::widen(AppUpdater::get_filename_from_url(txtctrl_path->GetValue().ToUTF8().data()))
+			, wildcard
+			, wxFD_SAVE | wxFD_OVERWRITE_PROMPT
+		);
+		if (save_dlg.ShowModal() == wxID_OK) {
+			txtctrl_path->SetValue(save_dlg.GetPath());
+		}
+	}));
+
+	content_sizer->SetMinSize(AppUpdateAvailableDialog::AUAD_size);
+
+	add_button(wxID_CANCEL);
+
+	if (auto* btn_ok = get_button(wxID_OK); btn_ok != NULL) {
+		btn_ok->SetLabel(_L("Download"));
+		btn_ok->Bind(wxEVT_BUTTON, ([this, path](wxCommandEvent& e){
+			if (boost::filesystem::exists(boost::filesystem::path(txtctrl_path->GetValue().ToUTF8().data()))) {
+				MessageDialog msgdlg(nullptr, GUI::format_wxstr(_L("File %1% already exists. Do you wish to overwrite it?"), txtctrl_path->GetValue()),_L("Notice"), wxYES_NO);
+				if (msgdlg.ShowModal() != wxID_YES)
+					return;
+			}
+			this->EndModal(wxID_OK);
+		}));
+	}
+
+
+	finalize();
+}
+
+AppUpdateDownloadDialog::~AppUpdateDownloadDialog() {}
+
+
+bool AppUpdateDownloadDialog::run_after_download() const
+{
+#ifndef __linux__
+	return cbox_run->GetValue();
+#endif
+	return false;
+}
+
+boost::filesystem::path AppUpdateDownloadDialog::get_download_path() const
+{
+	return std::move(boost::filesystem::path(txtctrl_path->GetValue().ToUTF8().data()));
+}
+
 // MsgUpdateConfig
 
 MsgUpdateConfig::MsgUpdateConfig(const std::vector<Update> &updates, bool force_before_wizard/* = false*/) :
@@ -314,5 +436,25 @@ MsgNoUpdates::MsgNoUpdates() :
 
 MsgNoUpdates::~MsgNoUpdates() {}
 
+// MsgNoAppUpdates
+MsgNoAppUpdates::MsgNoAppUpdates() :
+	MsgDialog(nullptr, _(L("App update")), _(L("No updates available")), wxICON_ERROR | wxOK)
+{
+
+	auto* text = new wxStaticText(this, wxID_ANY, wxString::Format(
+		_(L(
+			"%s has no version updates available."
+		)),
+		SLIC3R_APP_NAME
+	));
+	text->Wrap(CONTENT_WIDTH * wxGetApp().em_unit());
+	content_sizer->Add(text);
+	content_sizer->AddSpacer(VERT_SPACING);
+
+	finalize();
+}
+
+MsgNoAppUpdates::~MsgNoAppUpdates() {}
+
 }
 }
diff --git a/src/slic3r/GUI/UpdateDialogs.hpp b/src/slic3r/GUI/UpdateDialogs.hpp
index 435a8ccbd..2eb4ff8d4 100644
--- a/src/slic3r/GUI/UpdateDialogs.hpp
+++ b/src/slic3r/GUI/UpdateDialogs.hpp
@@ -6,6 +6,8 @@
 #include <vector>
 #include <wx/hyperlink.h>
 
+#include <boost/filesystem.hpp>
+
 #include "libslic3r/Semver.hpp"
 #include "MsgDialog.hpp"
 
@@ -37,6 +39,42 @@ private:
 };
 
 
+class AppUpdateAvailableDialog : public MsgDialog
+{
+public:
+	AppUpdateAvailableDialog(const Semver& ver_current, const Semver& ver_online);
+	AppUpdateAvailableDialog(AppUpdateAvailableDialog&&) = delete;
+	AppUpdateAvailableDialog(const AppUpdateAvailableDialog&) = delete;
+	AppUpdateAvailableDialog& operator=(AppUpdateAvailableDialog&&) = delete;
+	AppUpdateAvailableDialog& operator=(const AppUpdateAvailableDialog&) = delete;
+	virtual ~AppUpdateAvailableDialog();
+
+	// Tells whether the user checked the "don't bother me again" checkbox
+	bool disable_version_check() const;
+	static wxSize AUAD_size;
+private:
+	wxCheckBox* cbox;
+};
+
+class AppUpdateDownloadDialog : public MsgDialog
+{
+public:
+	AppUpdateDownloadDialog(const Semver& ver_online, boost::filesystem::path& path);
+	AppUpdateDownloadDialog(AppUpdateDownloadDialog&&) = delete;
+	AppUpdateDownloadDialog(const AppUpdateDownloadDialog&) = delete;
+	AppUpdateDownloadDialog& operator=(AppUpdateDownloadDialog&&) = delete;
+	AppUpdateDownloadDialog& operator=(const AppUpdateDownloadDialog&) = delete;
+	virtual ~AppUpdateDownloadDialog();
+
+	// Tells whether the user checked the "don't bother me again" checkbox
+	bool		run_after_download() const;
+	boost::filesystem::path	get_download_path() const;
+
+private:
+	wxCheckBox* cbox_run;
+	wxTextCtrl* txtctrl_path;
+};
+
 // Confirmation dialog informing about configuration update. Lists updated bundles & their versions.
 class MsgUpdateConfig : public MsgDialog
 {
@@ -129,6 +167,18 @@ public:
 	~MsgNoUpdates();
 };
 
+// Informs about absence of new version online.
+class MsgNoAppUpdates : public MsgDialog
+{
+public:
+	MsgNoAppUpdates();
+	MsgNoAppUpdates(MsgNoAppUpdates&&) = delete;
+	MsgNoAppUpdates(const MsgNoAppUpdates&) = delete;
+	MsgNoAppUpdates& operator=(MsgNoUpdates&&) = delete;
+	MsgNoAppUpdates& operator=(const MsgNoAppUpdates&) = delete;
+	~MsgNoAppUpdates();
+};
+
 }
 }
 
diff --git a/src/slic3r/Utils/AppUpdater.cpp b/src/slic3r/Utils/AppUpdater.cpp
new file mode 100644
index 000000000..60739ccb3
--- /dev/null
+++ b/src/slic3r/Utils/AppUpdater.cpp
@@ -0,0 +1,618 @@
+#include "AppUpdater.hpp"
+
+#include <atomic>
+#include <thread>
+
+#include <boost/filesystem.hpp>
+#include <boost/log/trivial.hpp>
+#include <boost/nowide/convert.hpp>
+#include <boost/property_tree/ini_parser.hpp> 
+#include <curl/curl.h>
+
+#include "slic3r/GUI/format.hpp"
+#include "slic3r/GUI/GUI_App.hpp"
+#include "slic3r/GUI/GUI.hpp"
+#include "slic3r/Utils/Http.hpp"
+
+#include "libslic3r/Utils.hpp"
+
+#ifdef _WIN32
+#include <shellapi.h>
+#include <Shlobj_core.h>
+#include <windows.h>
+#include <KnownFolders.h>
+#include <shlobj.h>
+#endif // _WIN32
+
+
+namespace Slic3r {
+
+namespace {
+	
+#ifdef _WIN32
+	bool run_file(const boost::filesystem::path& path)
+	{
+		std::string msg;
+		bool res = GUI::create_process(path, std::wstring(), msg);
+		if (!res) {
+			std::string full_message = GUI::format("Running downloaded instaler of %1% has failed:\n%2%", SLIC3R_APP_NAME, msg);
+			BOOST_LOG_TRIVIAL(error) << full_message; // lm: maybe UI error msg?  // dk: bellow. (maybe some general show error evt would be better?)
+			wxCommandEvent* evt = new wxCommandEvent(EVT_SLIC3R_APP_DOWNLOAD_FAILED);
+			evt->SetString(full_message);
+			GUI::wxGetApp().QueueEvent(evt);
+		}
+		return res;
+	}
+
+	std::string get_downloads_path()
+	{
+		std::string ret;
+		PWSTR path = NULL;
+		HRESULT hr = SHGetKnownFolderPath(FOLDERID_Downloads, 0, NULL, &path);
+		if (SUCCEEDED(hr)) {
+			ret = boost::nowide::narrow(path);
+		}
+		CoTaskMemFree(path);
+		return ret;
+	}
+#elif  __APPLE__
+	bool run_file(const boost::filesystem::path& path)
+	{
+		if (boost::filesystem::exists(path)) {
+			// attach downloaded dmg file
+            const char* argv1[] = { "hdiutil", "attach", path.string().c_str(), nullptr };
+            ::wxExecute(const_cast<char**>(argv1), wxEXEC_ASYNC, nullptr);
+            // open inside attached as a folder in finder
+            const char* argv2[] = { "open", "/Volumes/PrusaSlicer", nullptr };
+			::wxExecute(const_cast<char**>(argv2), wxEXEC_ASYNC, nullptr);
+			return true;
+		}
+		return false;
+	}
+
+	std::string get_downloads_path()
+	{
+		// call objective-c implementation
+		return get_downloads_path_mac();
+	}
+#else
+	bool run_file(const boost::filesystem::path& path)
+	{	
+		return false;
+	}
+
+	std::string get_downloads_path()
+	{
+		wxString command = "xdg-user-dir DOWNLOAD";
+		wxArrayString output;
+		GUI::desktop_execute_get_result(command, output);
+		if (output.GetCount() > 0) {
+			return output[0].ToUTF8().data(); //lm:I would use wxString::ToUTF8(), although on Linux, nothing at all should work too.
+		}
+		return std::string();
+	}
+#endif // _WIN32 / __apple__ / else 
+} // namespace
+
+wxDEFINE_EVENT(EVT_SLIC3R_VERSION_ONLINE, wxCommandEvent);
+wxDEFINE_EVENT(EVT_SLIC3R_EXPERIMENTAL_VERSION_ONLINE, wxCommandEvent);
+wxDEFINE_EVENT(EVT_SLIC3R_APP_DOWNLOAD_PROGRESS, wxCommandEvent);
+wxDEFINE_EVENT(EVT_SLIC3R_APP_DOWNLOAD_FAILED, wxCommandEvent);
+wxDEFINE_EVENT(EVT_SLIC3R_APP_OPEN_FAILED, wxCommandEvent);
+
+// priv handles all operations in separate thread
+// 1) download version file and parse it.
+// 2) download new app file and open in folder / run it.
+struct AppUpdater::priv {
+	priv();
+	// Download file. What happens with the data is specified in completefn.
+	bool http_get_file(const std::string& url
+		, size_t size_limit
+		, std::function<bool(Http::Progress)> progress_fn
+		, std::function<bool(std::string /*body*/, std::string& error_message)> completefn
+		, std::string& error_message
+	) const;
+
+	// Download installer / app
+	boost::filesystem::path download_file(const DownloadAppData& data) const;
+	// Run file in m_last_dest_path
+	bool run_downloaded_file(boost::filesystem::path path);
+	// gets version file via http
+	void version_check(const std::string& version_check_url);
+#if 0
+	// parsing of Prusaslicer.version2 
+	void parse_version_string_old(const std::string& body) const;
+#endif
+	// parses ini tree of version file, saves to m_online_version_data and queue event(s) to UI 
+	void parse_version_string(const std::string& body);
+	// thread
+	std::thread				m_thread;
+	std::atomic_bool        m_cancel;
+	std::mutex				m_data_mutex;
+	// used to tell if notify user hes about to stop ongoing download
+	std::atomic_bool		m_download_ongoing { false };
+	bool					get_download_ongoing() const { return m_download_ongoing; }
+	// read only variable used to init m_online_version_data.target_path
+	boost::filesystem::path m_default_dest_folder; // readonly
+	// DownloadAppData read / write needs to be locked by m_data_mutex
+	DownloadAppData			m_online_version_data;
+	DownloadAppData get_app_data();
+	void            set_app_data(DownloadAppData data);
+	// set only before version file is downloaded, to keep information to show info dialog about no updates
+	// should never change during thread run
+	std::atomic_bool		m_triggered_by_user {false};
+	bool					get_triggered_by_user() const { return m_triggered_by_user; }
+};
+
+AppUpdater::priv::priv() :
+	m_cancel (false)
+#ifdef __linux__
+    , m_default_dest_folder (boost::filesystem::path("/tmp"))
+#else
+	, m_default_dest_folder (boost::filesystem::path(data_dir()) / "cache")
+#endif //_WIN32
+{	
+	boost::filesystem::path downloads_path = boost::filesystem::path(get_downloads_path());
+	if (!downloads_path.empty()) {
+		m_default_dest_folder = std::move(downloads_path);
+	}
+	BOOST_LOG_TRIVIAL(trace) << "App updater default download path: " << m_default_dest_folder; //lm:Is this an error? // dk: changed to trace
+	
+}
+
+bool  AppUpdater::priv::http_get_file(const std::string& url, size_t size_limit, std::function<bool(Http::Progress)> progress_fn, std::function<bool(std::string /*body*/, std::string& error_message)> complete_fn, std::string& error_message) const
+{
+	bool res = false;
+	Http::get(url)
+		.size_limit(size_limit)
+		.on_progress([&, progress_fn](Http::Progress progress, bool& cancel) {
+			// progress function returns true as success (to continue) 
+			cancel = (this->m_cancel ? true : !progress_fn(std::move(progress)));
+			if (cancel) {
+				error_message = GUI::format("Error getting: `%1%`: Download was canceled.", //lm:typo //dk: am i blind? :)
+					url);
+				BOOST_LOG_TRIVIAL(debug) << "AppUpdater::priv::http_get_file message: "<< error_message;
+			}
+		})
+		.on_error([&](std::string body, std::string error, unsigned http_status) {
+			error_message = GUI::format("Error getting: `%1%`: HTTP %2%, %3%",
+				url,
+				http_status,
+				error);
+			BOOST_LOG_TRIVIAL(error) << error_message;
+		})
+		.on_complete([&](std::string body, unsigned /* http_status */) {
+			assert(complete_fn != nullptr);
+			res = complete_fn(body, error_message);
+		})
+		.perform_sync();
+	
+	return res;
+}
+
+boost::filesystem::path AppUpdater::priv::download_file(const DownloadAppData& data) const
+{
+	boost::filesystem::path dest_path;
+	size_t last_gui_progress = 0;
+	size_t expected_size = data.size;
+	dest_path = data.target_path;
+	assert(!dest_path.empty());
+	if (dest_path.empty())
+	{
+		BOOST_LOG_TRIVIAL(error) << "Download from " << data.url << " could not start. Destination path is empty.";
+		return boost::filesystem::path();
+	}
+	std::string error_message;
+	bool res = http_get_file(data.url, 130 * 1024 * 1024 //2.4.0 windows installer is 65MB //lm:I don't know, but larger. The binaries will grow. // dk: changed to 130, to have 100% more space. We should put this information into version file. 
+		// on_progress
+		, [&last_gui_progress, expected_size](Http::Progress progress) {
+			// size check
+			if (progress.dltotal > 0 && progress.dltotal > expected_size) {
+				std::string message = GUI::format("Downloading new %1% has failed. The file has incorrect file size. Aborting download.\nExpected size: %2%\nDownload size: %3%", SLIC3R_APP_NAME, expected_size, progress.dltotal);
+				BOOST_LOG_TRIVIAL(error) << message;
+				wxCommandEvent* evt = new wxCommandEvent(EVT_SLIC3R_APP_DOWNLOAD_FAILED);
+				evt->SetString(message);
+				GUI::wxGetApp().QueueEvent(evt);
+				return false;
+			} else if (progress.dltotal > 0 && progress.dltotal < expected_size) { 
+				//lm:When will this happen? Is that not an error? // dk: It is possible error, but we cannot know until the download is finished. Somehow the total size can grow during the download.
+				BOOST_LOG_TRIVIAL(info) << GUI::format("Downloading new %1% has incorrect size. The download will continue. \nExpected size: %2%\nDownload size: %3%", SLIC3R_APP_NAME, expected_size, progress.dltotal);
+			} 
+			// progress event
+			size_t gui_progress = progress.dltotal > 0 ? 100 * progress.dlnow / progress.dltotal : 0;
+			BOOST_LOG_TRIVIAL(error) << "App download " << gui_progress << "% " << progress.dlnow << " of " << progress.dltotal;
+			if (last_gui_progress < gui_progress && (last_gui_progress != 0 || gui_progress != 100)) {
+				last_gui_progress = gui_progress;
+				wxCommandEvent* evt = new wxCommandEvent(EVT_SLIC3R_APP_DOWNLOAD_PROGRESS);
+				evt->SetString(GUI::from_u8(std::to_string(gui_progress)));
+				GUI::wxGetApp().QueueEvent(evt);
+			}
+			return true;
+		}
+		// on_complete
+		, [dest_path, expected_size](std::string body, std::string& error_message){
+			// Size check. Does always 1 char == 1 byte?
+			size_t body_size = body.size(); 
+			if (body_size != expected_size) {
+				//lm:UI message? // dk: changed. Now it propagates to UI.
+				error_message = GUI::format("Downloaded file has wrong size. Expected size: %1% Downloaded size: %2%", expected_size, body_size);
+				return false;
+			}
+			boost::filesystem::path tmp_path = dest_path;
+			tmp_path += format(".%1%%2%", get_current_pid(), ".download");
+			try
+			{
+				boost::filesystem::fstream file(tmp_path, std::ios::out | std::ios::binary | std::ios::trunc);
+				file.write(body.c_str(), body.size());
+				file.close();
+				boost::filesystem::rename(tmp_path, dest_path);
+			}
+			catch (const std::exception&)
+			{
+				error_message = GUI::format("Failed to write and move %1% to %2%", tmp_path, dest_path);
+				return false;
+			}
+			return true;
+		}
+		, error_message
+	);
+	if (!res)
+	{
+		if (this->m_cancel)
+		{
+			BOOST_LOG_TRIVIAL(info) << error_message; //lm:Is this an error? // dk: changed to info
+			wxCommandEvent* evt = new wxCommandEvent(EVT_SLIC3R_APP_DOWNLOAD_FAILED); // FAILED with empty msg only closes progress notification
+			GUI::wxGetApp().QueueEvent(evt);
+		} else {
+			std::string message = GUI::format("Downloading new %1% has failed:\n%2%", SLIC3R_APP_NAME, error_message);
+			BOOST_LOG_TRIVIAL(error) << message;
+			wxCommandEvent* evt = new wxCommandEvent(EVT_SLIC3R_APP_DOWNLOAD_FAILED);
+			evt->SetString(message);
+			GUI::wxGetApp().QueueEvent(evt);
+		}
+		return boost::filesystem::path();
+	}
+	
+	return dest_path;
+}
+
+bool AppUpdater::priv::run_downloaded_file(boost::filesystem::path path)
+{
+	assert(!path.empty());
+	return run_file(path);
+}
+
+void AppUpdater::priv::version_check(const std::string& version_check_url) 
+{
+	assert(!version_check_url.empty());
+	std::string error_message;
+	bool res = http_get_file(version_check_url, 1024
+		// on_progress
+		, [](Http::Progress progress) { return true; }
+		// on_complete
+		, [&](std::string body, std::string& error_message) {
+			boost::trim(body);
+			parse_version_string(body);
+			return true;
+		}
+		, error_message
+	);
+	//lm:In case the internet is not available, it will report no updates if run by user.
+	// We might save a flag that we don't know or try to run the version_check again, reporting
+	// the failure.
+	// dk: changed to download version every time. Dialog will show if m_triggered_by_user.
+	if (!res) {
+		std::string message = GUI::format("Downloading %1% version file has failed:\n%2%", SLIC3R_APP_NAME, error_message);
+		BOOST_LOG_TRIVIAL(error) << message;
+		if (m_triggered_by_user) {
+			wxCommandEvent* evt = new wxCommandEvent(EVT_SLIC3R_APP_DOWNLOAD_FAILED);
+			evt->SetString(message);
+			GUI::wxGetApp().QueueEvent(evt);
+		}
+	}
+}
+
+void AppUpdater::priv::parse_version_string(const std::string& body)
+{
+	size_t start = body.find('[');
+	if (start == std::string::npos) {
+#if 0
+		BOOST_LOG_TRIVIAL(error) << "Could not find property tree in version file. Starting old parsing.";
+		parse_version_string_old(body);
+		return;
+#endif // 0
+		BOOST_LOG_TRIVIAL(error) << "Could not find property tree in version file. Checking for application update has failed.";
+		return;
+	}
+	std::string tree_string = body.substr(start);
+	boost::property_tree::ptree tree;
+	std::stringstream ss(tree_string);
+	try {
+		boost::property_tree::read_ini(ss, tree);
+	} catch (const boost::property_tree::ini_parser::ini_parser_error& err) {
+		//throw Slic3r::RuntimeError(format("Failed reading version file property tree Error: \"%1%\" at line %2%. \nTree:\n%3%", err.message(), err.line(), tree_string).c_str());
+		BOOST_LOG_TRIVIAL(error) << format("Failed reading version file property tree Error: \"%1%\" at line %2%. \nTree:\n%3%", err.message(), err.line(), tree_string);
+		return;
+	}
+
+	DownloadAppData new_data;
+
+	for (const auto& section : tree) {
+		std::string section_name = section.first;
+
+		// online release version info
+		if (section_name == 
+#ifdef _WIN32
+			"release:win64"
+#elif __APPLE__
+			"release:osx"
+#else
+			"release:linux"
+#endif
+//lm:Related to the ifdefs. We should also support BSD, which behaves similar to Linux in most cases.
+// Unless you have a reason not to, I would consider doing _WIN32, elif __APPLE__, else ... Not just here.
+// dk: so its ok now or we need to specify BSD?
+			) {
+			for (const auto& data : section.second) {
+				if (data.first == "url") {
+					new_data.url = data.second.data();
+					new_data.target_path = m_default_dest_folder / AppUpdater::get_filename_from_url(new_data.url);
+					BOOST_LOG_TRIVIAL(error) << format("parsing version string: url: %1%", new_data.url);
+				} else if (data.first == "size"){
+					new_data.size = std::stoi(data.second.data());
+					BOOST_LOG_TRIVIAL(error) << format("parsing version string: expected size: %1%", new_data.size);
+				}
+			}
+		}
+
+		// released versions - to be send to UI layer
+		if (section_name == "common") {
+			std::vector<std::string> prerelease_versions;
+			for (const auto& data : section.second) {
+				// release version - save and send to UI layer
+				if (data.first == "release") {
+					std::string version = data.second.data();
+					boost::optional<Semver> release_version = Semver::parse(version);
+					if (!release_version) {
+						BOOST_LOG_TRIVIAL(error) << format("Received invalid contents from version file: Not a correct semver: `%1%`", version);
+						return;
+					}
+					new_data.version = release_version;
+					// Send after all data is read
+					/*
+					BOOST_LOG_TRIVIAL(info) << format("Got %1% online version: `%2%`. Sending to GUI thread...", SLIC3R_APP_NAME, version);
+					wxCommandEvent* evt = new wxCommandEvent(EVT_SLIC3R_VERSION_ONLINE);
+					evt->SetString(GUI::from_u8(version));
+					GUI::wxGetApp().QueueEvent(evt);
+					*/
+				// prerelease versions - write down to be sorted and send to UI layer
+				} else if (data.first == "alpha") {
+					prerelease_versions.emplace_back(data.second.data());
+				} else if (data.first == "beta") {
+					prerelease_versions.emplace_back(data.second.data());
+				} else if (data.first == "rc") {
+					prerelease_versions.emplace_back(data.second.data());
+				}
+			}
+			// find recent version that is newer than last full release.
+			boost::optional<Semver> recent_version;
+			std::string				version_string;
+			for (const std::string& ver_string : prerelease_versions) {
+				boost::optional<Semver> ver = Semver::parse(ver_string);
+				if (ver && *new_data.version < *ver && ((recent_version && *recent_version < *ver) || !recent_version)) {
+					recent_version = ver;
+					version_string = ver_string;
+				}
+			}
+			// send prerelease version to UI layer
+			if (recent_version) {
+				BOOST_LOG_TRIVIAL(info) << format("Got %1% online version: `%2%`. Sending to GUI thread...", SLIC3R_APP_NAME, version_string);
+				wxCommandEvent* evt = new wxCommandEvent(EVT_SLIC3R_EXPERIMENTAL_VERSION_ONLINE);
+				evt->SetString(GUI::from_u8(version_string));
+				GUI::wxGetApp().QueueEvent(evt);
+			}
+		}
+	}
+	assert(!new_data.url.empty());
+	assert(new_data.version);
+	// save
+	set_app_data(new_data);
+	// send
+	std::string version = new_data.version.get().to_string();
+	BOOST_LOG_TRIVIAL(info) << format("Got %1% online version: `%2%`. Sending to GUI thread...", SLIC3R_APP_NAME, version);
+	wxCommandEvent* evt = new wxCommandEvent(EVT_SLIC3R_VERSION_ONLINE);
+	evt->SetString(GUI::from_u8(version));
+	GUI::wxGetApp().QueueEvent(evt);
+}
+
+#if 0 //lm:is this meant to be ressurected? //dk: it is code that parses PrusaSlicer.version2 in 2.4.0, It was deleted from PresetUpdater.cpp and I would keep it here for possible reference.
+void AppUpdater::priv::parse_version_string_old(const std::string& body) const
+{
+
+	// release version
+	std::string version;
+	const auto first_nl_pos = body.find_first_of("\n\r");
+	if (first_nl_pos != std::string::npos)
+		version = body.substr(0, first_nl_pos);
+	else
+		version = body;
+	boost::optional<Semver> release_version = Semver::parse(version);
+	if (!release_version) {
+		BOOST_LOG_TRIVIAL(error) << format("Received invalid contents from `%1%`: Not a correct semver: `%2%`", SLIC3R_APP_NAME, version);
+		return;
+	}
+	BOOST_LOG_TRIVIAL(info) << format("Got %1% online version: `%2%`. Sending to GUI thread...", SLIC3R_APP_NAME, version);
+	wxCommandEvent* evt = new wxCommandEvent(EVT_SLIC3R_VERSION_ONLINE);
+	evt->SetString(GUI::from_u8(version));
+	GUI::wxGetApp().QueueEvent(evt);
+
+	// alpha / beta version
+	std::vector<std::string> prerelease_versions;
+	size_t nexn_nl_pos = first_nl_pos;
+	while (nexn_nl_pos != std::string::npos && body.size() > nexn_nl_pos + 1) {
+		const auto last_nl_pos = nexn_nl_pos;
+		nexn_nl_pos = body.find_first_of("\n\r", last_nl_pos + 1);
+		std::string line;
+		if (nexn_nl_pos == std::string::npos)
+			line = body.substr(last_nl_pos + 1);
+		else
+			line = body.substr(last_nl_pos + 1, nexn_nl_pos - last_nl_pos - 1);
+
+		// alpha
+		if (line.substr(0, 6) == "alpha=") {
+			version = line.substr(6);
+			if (!Semver::parse(version)) {
+				BOOST_LOG_TRIVIAL(error) << format("Received invalid contents for alpha release from `%1%`: Not a correct semver: `%2%`", SLIC3R_APP_NAME, version);
+				return;
+			}
+			prerelease_versions.emplace_back(version);
+			// beta
+		}
+		else if (line.substr(0, 5) == "beta=") {
+			version = line.substr(5);
+			if (!Semver::parse(version)) {
+				BOOST_LOG_TRIVIAL(error) << format("Received invalid contents for beta release from `%1%`: Not a correct semver: `%2%`", SLIC3R_APP_NAME, version);
+				return;
+			}
+			prerelease_versions.emplace_back(version);
+		}
+	}
+	// find recent version that is newer than last full release.
+	boost::optional<Semver> recent_version;
+	for (const std::string& ver_string : prerelease_versions) {
+		boost::optional<Semver> ver = Semver::parse(ver_string);
+		if (ver && *release_version < *ver && ((recent_version && *recent_version < *ver) || !recent_version)) {
+			recent_version = ver;
+			version = ver_string;
+		}
+	}
+	if (recent_version) {
+		BOOST_LOG_TRIVIAL(info) << format("Got %1% online version: `%2%`. Sending to GUI thread...", SLIC3R_APP_NAME, version);
+		wxCommandEvent* evt = new wxCommandEvent(EVT_SLIC3R_EXPERIMENTAL_VERSION_ONLINE);
+		evt->SetString(GUI::from_u8(version));
+		GUI::wxGetApp().QueueEvent(evt);
+	}
+}
+#endif // 0
+
+DownloadAppData AppUpdater::priv::get_app_data()
+{
+	const std::lock_guard<std::mutex> lock(m_data_mutex);
+	DownloadAppData ret_val(m_online_version_data);
+	return ret_val;
+}
+
+void AppUpdater::priv::set_app_data(DownloadAppData data)
+{
+	const std::lock_guard<std::mutex> lock(m_data_mutex);
+	m_online_version_data = data;
+}
+
+AppUpdater::AppUpdater()
+	:p(new priv())
+{
+}
+AppUpdater::~AppUpdater()
+{
+	if (p && p->m_thread.joinable()) {
+		// This will stop transfers being done by the thread, if any.
+		// Cancelling takes some time, but should complete soon enough.
+		p->m_cancel = true;
+		p->m_thread.join();
+	}
+}
+void AppUpdater::sync_download()
+{
+	assert(p);
+	// join thread first - it could have been in sync_version
+	if (p->m_thread.joinable()) {
+		// This will stop transfers being done by the thread, if any.
+		// Cancelling takes some time, but should complete soon enough.
+		p->m_cancel = true;
+		p->m_thread.join();
+	}
+	p->m_cancel = false;
+
+	DownloadAppData input_data = p->get_app_data();
+	assert(!input_data.url.empty());
+
+ 	p->m_thread = std::thread(
+		[this, input_data]() {
+			p->m_download_ongoing = true;
+			if (boost::filesystem::path dest_path = p->download_file(input_data); boost::filesystem::exists(dest_path)){
+				if (input_data.start_after) {
+					p->run_downloaded_file(std::move(dest_path));
+				} else {
+					GUI::desktop_open_folder(dest_path.parent_path());
+				}
+			}
+			p->m_download_ongoing = false;
+		});
+}
+
+void AppUpdater::sync_version(const std::string& version_check_url, bool from_user)
+{
+	assert(p);
+	// join thread first - it could have been in sync_download
+	if (p->m_thread.joinable()) {
+		// This will stop transfers being done by the thread, if any.
+		// Cancelling takes some time, but should complete soon enough.
+		p->m_cancel = true;
+		p->m_thread.join();
+	}
+	p->m_triggered_by_user = from_user;
+	p->m_cancel = false;
+	p->m_thread = std::thread(
+		[this, version_check_url]() {
+			p->version_check(version_check_url);
+		});
+}
+
+void AppUpdater::cancel()
+{
+	p->m_cancel = true;
+}
+bool AppUpdater::cancel_callback()
+{
+	cancel();
+	return true;
+}
+
+std::string AppUpdater::get_default_dest_folder()
+{
+	return p->m_default_dest_folder.string();
+}
+
+std::string AppUpdater::get_filename_from_url(const std::string& url)
+{
+	size_t slash = url.rfind('/');
+	return (slash != std::string::npos ? url.substr(slash + 1) : url);
+}
+
+std::string AppUpdater::get_file_extension_from_url(const std::string& url)
+{
+	size_t dot = url.rfind('.');
+	return (dot != std::string::npos ? url.substr(dot) : url);
+}
+
+void AppUpdater::set_app_data(DownloadAppData data)
+{
+	p->set_app_data(std::move(data));
+}
+
+DownloadAppData AppUpdater::get_app_data()
+{
+	return p->get_app_data();
+}
+
+bool AppUpdater::get_triggered_by_user() const
+{
+	return p->get_triggered_by_user();
+}
+
+bool AppUpdater::get_download_ongoing() const
+{
+	return p->get_download_ongoing();
+}
+
+} //namespace Slic3r 
diff --git a/src/slic3r/Utils/AppUpdater.hpp b/src/slic3r/Utils/AppUpdater.hpp
new file mode 100644
index 000000000..16d0d668f
--- /dev/null
+++ b/src/slic3r/Utils/AppUpdater.hpp
@@ -0,0 +1,66 @@
+#ifndef slic3r_AppUpdate_hpp_
+#define slic3r_AppUpdate_hpp_
+
+#include <boost/filesystem.hpp>
+#include <boost/optional.hpp>
+#include "libslic3r/Utils.hpp"
+#include "wx/event.h"
+
+//class boost::filesystem::path;
+
+namespace Slic3r {
+
+#ifdef __APPLE__
+// implmented at MacUtils.mm
+std::string get_downloads_path_mac();
+#endif //__APPLE__
+
+struct DownloadAppData
+{
+	std::string				url;
+	bool					start_after;
+	boost::optional<Semver> version;
+	size_t				    size;
+	boost::filesystem::path target_path;
+};
+
+class AppUpdater
+{
+public:
+	AppUpdater();
+	~AppUpdater();
+	AppUpdater(AppUpdater&&) = delete;
+	AppUpdater(const AppUpdater&) = delete;
+	AppUpdater& operator=(AppUpdater&&) = delete;
+	AppUpdater& operator=(const AppUpdater&) = delete;
+
+	// downloads app file
+	void sync_download();
+	// downloads version file
+	void sync_version(const std::string& version_check_url, bool from_user);
+	void cancel();
+	bool cancel_callback();
+
+	std::string get_default_dest_folder();
+
+	static std::string get_filename_from_url(const std::string& url);
+	static std::string get_file_extension_from_url(const std::string& url);
+
+	// atomic bool
+	bool				get_triggered_by_user() const;
+	bool				get_download_ongoing() const;
+	// mutex access
+	void				set_app_data(DownloadAppData data);
+	DownloadAppData		get_app_data();
+private:
+	struct priv;
+	std::unique_ptr<priv> p;
+};
+
+wxDECLARE_EVENT(EVT_SLIC3R_VERSION_ONLINE, wxCommandEvent);
+wxDECLARE_EVENT(EVT_SLIC3R_EXPERIMENTAL_VERSION_ONLINE, wxCommandEvent);
+wxDECLARE_EVENT(EVT_SLIC3R_APP_DOWNLOAD_PROGRESS, wxCommandEvent);
+wxDECLARE_EVENT(EVT_SLIC3R_APP_DOWNLOAD_FAILED, wxCommandEvent);
+wxDECLARE_EVENT(EVT_SLIC3R_APP_OPEN_FAILED, wxCommandEvent);
+} //namespace Slic3r 
+#endif
diff --git a/src/slic3r/Utils/Http.cpp b/src/slic3r/Utils/Http.cpp
index 63c26f721..68ddda041 100644
--- a/src/slic3r/Utils/Http.cpp
+++ b/src/slic3r/Utils/Http.cpp
@@ -207,7 +207,6 @@ size_t Http::priv::writecb(void *data, size_t size, size_t nmemb, void *userp)
 	auto self = static_cast<priv*>(userp);
 	const char *cdata = static_cast<char*>(data);
 	const size_t realsize = size * nmemb;
-
 	const size_t limit = self->limit > 0 ? self->limit : DEFAULT_SIZE_LIMIT;
 	if (self->buffer.size() + realsize > limit) {
 		// This makes curl_easy_perform return CURLE_WRITE_ERROR
diff --git a/src/slic3r/Utils/MacUtils.mm b/src/slic3r/Utils/MacUtils.mm
new file mode 100644
index 000000000..31a28f14e
--- /dev/null
+++ b/src/slic3r/Utils/MacUtils.mm
@@ -0,0 +1,18 @@
+#import "AppUpdater.hpp"
+
+#import <Foundation/Foundation.h>
+
+namespace Slic3r {
+
+// AppUpdater.hpp
+std::string get_downloads_path_mac()
+{
+	// 1)
+	NSArray * paths = NSSearchPathForDirectoriesInDomains (NSDownloadsDirectory, NSUserDomainMask, YES);
+	NSString * desktopPath = [paths objectAtIndex:0];
+    return std::string([desktopPath UTF8String]);
+	// 2)
+	//[NSURL fileURLWithPath:[NSHomeDirectory() stringByAppendingPathComponent:@"Downloads"]];
+	//return std::string();
+}
+}
diff --git a/src/slic3r/Utils/PresetUpdater.cpp b/src/slic3r/Utils/PresetUpdater.cpp
index 2b458df53..f4863ff20 100644
--- a/src/slic3r/Utils/PresetUpdater.cpp
+++ b/src/slic3r/Utils/PresetUpdater.cpp
@@ -135,10 +135,6 @@ struct Updates
 	std::vector<Update> updates;
 };
 
-
-wxDEFINE_EVENT(EVT_SLIC3R_VERSION_ONLINE, wxCommandEvent);
-wxDEFINE_EVENT(EVT_SLIC3R_EXPERIMENTAL_VERSION_ONLINE, wxCommandEvent);
-
 struct PresetUpdater::priv
 {
 	std::vector<Index> index_db;
@@ -162,8 +158,6 @@ struct PresetUpdater::priv
 	void set_download_prefs(AppConfig *app_config);
 	bool get_file(const std::string &url, const fs::path &target_path) const;
 	void prune_tmps() const;
-	void sync_version() const;
-	void parse_version_string(const std::string& body) const;
 	void sync_config(const VendorMap vendors);
 
 	void check_install_indices() const;
@@ -238,101 +232,6 @@ void PresetUpdater::priv::prune_tmps() const
 		}
 }
 
-// Get Slic3rPE version available online, save in AppConfig.
-void PresetUpdater::priv::sync_version() const
-{
-	if (! enabled_version_check) { return; }
-
-	BOOST_LOG_TRIVIAL(info) << format("Downloading %1% online version from: `%2%`", SLIC3R_APP_NAME, version_check_url);
-
-	Http::get(version_check_url)
-		.size_limit(SLIC3R_VERSION_BODY_MAX)
-		.on_progress([this](Http::Progress, bool &cancel) {
-			cancel = this->cancel;
-		})
-		.on_error([&](std::string body, std::string error, unsigned http_status) {
-			(void)body;
-			BOOST_LOG_TRIVIAL(error) << format("Error getting: `%1%`: HTTP %2%, %3%",
-				version_check_url,
-				http_status,
-				error);
-		})
-		.on_complete([&](std::string body, unsigned /* http_status */) {
-			boost::trim(body);
-			parse_version_string(body);
-		})
-		.perform_sync();
-}
-
-// Parses version string obtained in sync_version() and sends events to UI thread.
-// Version string must contain release version on first line. Follows non-mandatory alpha / beta releases on following lines (alpha=2.0.0-alpha1).
-void PresetUpdater::priv::parse_version_string(const std::string& body) const
-{
-	// release version
-	std::string version;
-	const auto first_nl_pos = body.find_first_of("\n\r");
-	if (first_nl_pos != std::string::npos)
-		version = body.substr(0, first_nl_pos);
-	else
-		version = body;
-	boost::optional<Semver> release_version = Semver::parse(version);
-	if (!release_version) {
-		BOOST_LOG_TRIVIAL(error) << format("Received invalid contents from `%1%`: Not a correct semver: `%2%`", SLIC3R_APP_NAME, version);
-		return;
-	}
-	BOOST_LOG_TRIVIAL(info) << format("Got %1% online version: `%2%`. Sending to GUI thread...", SLIC3R_APP_NAME, version);
-	wxCommandEvent* evt = new wxCommandEvent(EVT_SLIC3R_VERSION_ONLINE);
-	evt->SetString(GUI::from_u8(version));
-	GUI::wxGetApp().QueueEvent(evt);
-
-	// alpha / beta version
-	std::vector<std::string> prerelease_versions;
-	size_t nexn_nl_pos = first_nl_pos;
-	while (nexn_nl_pos != std::string::npos && body.size() > nexn_nl_pos + 1) {
-		const auto last_nl_pos = nexn_nl_pos;
-		nexn_nl_pos = body.find_first_of("\n\r", last_nl_pos + 1);
-		std::string line;
-		if (nexn_nl_pos == std::string::npos)
-			line = body.substr(last_nl_pos + 1);
-		else
-			line = body.substr(last_nl_pos + 1, nexn_nl_pos - last_nl_pos - 1);
-
-		// alpha
-		if (line.substr(0, 6) == "alpha=") {
-			version = line.substr(6);
-			if (!Semver::parse(version)) {
-				BOOST_LOG_TRIVIAL(error) << format("Received invalid contents for alpha release from `%1%`: Not a correct semver: `%2%`", SLIC3R_APP_NAME, version);
-				return;
-			}
-			prerelease_versions.emplace_back(version);
-		// beta
-		}
-		else if (line.substr(0, 5) == "beta=") {
-			version = line.substr(5);
-			if (!Semver::parse(version)) {
-				BOOST_LOG_TRIVIAL(error) << format("Received invalid contents for beta release from `%1%`: Not a correct semver: `%2%`", SLIC3R_APP_NAME, version);
-				return;
-			}
-			prerelease_versions.emplace_back(version);
-		}
-	}
-	// find recent version that is newer than last full release.
-	boost::optional<Semver> recent_version;
-	for (const std::string& ver_string : prerelease_versions) {
-		boost::optional<Semver> ver = Semver::parse(ver_string);
-		if (ver && *release_version < *ver && ((recent_version && *recent_version < *ver) || !recent_version)) {
-			recent_version = ver;
-			version = ver_string;
-		}
-	}
-	if (recent_version) {
-		BOOST_LOG_TRIVIAL(info) << format("Got %1% online version: `%2%`. Sending to GUI thread...", SLIC3R_APP_NAME, version);
-		wxCommandEvent* evt = new wxCommandEvent(EVT_SLIC3R_EXPERIMENTAL_VERSION_ONLINE);
-		evt->SetString(GUI::from_u8(version));
-		GUI::wxGetApp().QueueEvent(evt);
-	}
-}
-
 // Download vendor indices. Also download new bundles if an index indicates there's a new one available.
 // Both are saved in cache.
 void PresetUpdater::priv::sync_config(const VendorMap vendors)
@@ -743,7 +642,6 @@ void PresetUpdater::sync(PresetBundle *preset_bundle)
 
     p->thread = std::thread([this, vendors]() {
 		this->p->prune_tmps();
-		this->p->sync_version();
 		this->p->sync_config(std::move(vendors));
     });
 }
diff --git a/src/slic3r/Utils/PresetUpdater.hpp b/src/slic3r/Utils/PresetUpdater.hpp
index 97d85a4ea..974a7dcfa 100644
--- a/src/slic3r/Utils/PresetUpdater.hpp
+++ b/src/slic3r/Utils/PresetUpdater.hpp
@@ -65,7 +65,7 @@ private:
 	std::unique_ptr<priv> p;
 };
 
-wxDECLARE_EVENT(EVT_SLIC3R_VERSION_ONLINE, wxCommandEvent);
-wxDECLARE_EVENT(EVT_SLIC3R_EXPERIMENTAL_VERSION_ONLINE, wxCommandEvent);
+//wxDECLARE_EVENT(EVT_SLIC3R_VERSION_ONLINE, wxCommandEvent);
+//wxDECLARE_EVENT(EVT_SLIC3R_EXPERIMENTAL_VERSION_ONLINE, wxCommandEvent);
 }
 #endif
diff --git a/tests/libslic3r/test_voronoi.cpp b/tests/libslic3r/test_voronoi.cpp
index db12e2fec..7f25797f5 100644
--- a/tests/libslic3r/test_voronoi.cpp
+++ b/tests/libslic3r/test_voronoi.cpp
@@ -2055,6 +2055,50 @@ TEST_CASE("Voronoi missing vertex 3", "[VoronoiMissingVertex3]")
 //    REQUIRE(!has_missing_voronoi_vertices(poly, vd));
 }
 
+TEST_CASE("Voronoi missing vertex 4", "[VoronoiMissingVertex4]")
+{
+    // Probably the reason why Voronoi vertex is missing is that 19299999 and 19300000 are very close.
+    Polygon polygon_1 = {
+        Point(27000000, -18900000),
+        Point(27000000, 20000000),
+        Point(19000000, 20000000),
+        Point(19000000, 19299999),
+        Point(26000000, -18000000),
+        Point(-19000000, -18000000),
+        Point(-27000000, 19300000),
+        Point(-19000000, 19300000),
+        Point(-19000000, 20000000),
+        Point(-28000000, 20000000),
+        Point(-20000000, -18900000),
+    };
+
+    // Maybe this is the same case as the previous, but the missing Voronoi vertex is different.
+    Polygon polygon_2 = {
+        Point(27000000, -18900000),
+        Point(27000000, 20000000),
+        Point(19000000, 20000000),
+        Point(19000000, 19299999),
+        Point(19000000, -18000000), // Just this point is different other points are the same as previous.
+        Point(-19000000, -18000000),
+        Point(-27000000, 19300000),
+        Point(-19000000, 19300000),
+        Point(-19000000, 20000000),
+        Point(-28000000, 20000000),
+        Point(-20000000, -18900000),
+    };
+
+    Geometry::VoronoiDiagram vd_1;
+    Geometry::VoronoiDiagram vd_2;
+    Lines                    lines_1 = to_lines(polygon_1);
+    Lines                    lines_2 = to_lines(polygon_2);
+    construct_voronoi(lines_1.begin(), lines_1.end(), &vd_1);
+    construct_voronoi(lines_2.begin(), lines_2.end(), &vd_2);
+#ifdef VORONOI_DEBUG_OUT
+    dump_voronoi_to_svg(debug_out_path("voronoi-missing-vertex4-1-out.svg").c_str(), vd_1, Points(), lines_1);
+    dump_voronoi_to_svg(debug_out_path("voronoi-missing-vertex4-2-out.svg").c_str(), vd_2, Points(), lines_2);
+#endif
+}
+
 // In this case, the Voronoi vertex (146873, -146873) is included twice.
 // Also, near to those duplicate Voronoi vertices is another Voronoi vertex (146872, -146872).
 // Rotating the polygon will help solve this problem, but then there arise three very close Voronoi vertices.