diff --git a/src/libslic3r/Technologies.hpp b/src/libslic3r/Technologies.hpp
index 14e2a8bde..9b9067af3 100644
--- a/src/libslic3r/Technologies.hpp
+++ b/src/libslic3r/Technologies.hpp
@@ -10,6 +10,8 @@
 #define ENABLE_MODELINSTANCE_3D_FULL_TRANSFORM (1 && ENABLE_1_42_0)
 // Add double click on gizmo grabbers to reset transformation components to their default value
 #define ENABLE_GIZMOS_RESET (1 && ENABLE_1_42_0)
+// Uses a unique opengl context
+#define ENABLE_USE_UNIQUE_GLCONTEXT (1 && ENABLE_1_42_0)
 
 #endif // _technologies_h_
 
diff --git a/src/slic3r/GUI/Event.hpp b/src/slic3r/GUI/Event.hpp
index 63800fa00..2ae9fd154 100644
--- a/src/slic3r/GUI/Event.hpp
+++ b/src/slic3r/GUI/Event.hpp
@@ -14,6 +14,7 @@ struct SimpleEvent : public wxEvent
 {
     SimpleEvent(wxEventType type, wxObject* origin = nullptr) : wxEvent(0, type)
     {
+        m_propagationLevel = wxEVENT_PROPAGATE_MAX;
         SetEventObject(origin);
     }
 
@@ -30,6 +31,7 @@ template<class T, size_t N> struct ArrayEvent : public wxEvent
     ArrayEvent(wxEventType type, std::array<T, N> data, wxObject* origin = nullptr)
         : wxEvent(0, type), data(std::move(data))
     {
+        m_propagationLevel = wxEVENT_PROPAGATE_MAX;
         SetEventObject(origin);
     }
 
@@ -45,6 +47,7 @@ template<class T> struct ArrayEvent<T, 1> : public wxEvent
     ArrayEvent(wxEventType type, T data, wxObject* origin = nullptr)
         : wxEvent(0, type), data(std::move(data))
     {
+        m_propagationLevel = wxEVENT_PROPAGATE_MAX;
         SetEventObject(origin);
     }
 
diff --git a/src/slic3r/GUI/GLCanvas3D.cpp b/src/slic3r/GUI/GLCanvas3D.cpp
index 5a28ee5c0..b147ce989 100644
--- a/src/slic3r/GUI/GLCanvas3D.cpp
+++ b/src/slic3r/GUI/GLCanvas3D.cpp
@@ -317,6 +317,7 @@ bool GLCanvas3D::Bed::set_shape(const Pointfs& shape)
     if (m_shape == shape && m_type == new_type)
         // No change, no need to update the UI.
         return false;
+
     m_shape = shape;
     m_type = new_type;
 
@@ -1957,7 +1958,6 @@ wxDEFINE_EVENT(EVT_GIZMO_SCALE, Vec3dEvent);
 wxDEFINE_EVENT(EVT_GIZMO_ROTATE, Vec3dEvent);
 wxDEFINE_EVENT(EVT_GIZMO_FLATTEN, Vec3dEvent);
 
-
 GLCanvas3D::GLCanvas3D(wxGLCanvas* canvas)
     : m_canvas(canvas)
     , m_context(nullptr)
@@ -1987,7 +1987,9 @@ GLCanvas3D::GLCanvas3D(wxGLCanvas* canvas)
 {
     if (m_canvas != nullptr)
     {
+#if !ENABLE_USE_UNIQUE_GLCONTEXT
         m_context = new wxGLContext(m_canvas);
+#endif // !ENABLE_USE_UNIQUE_GLCONTEXT
         m_timer = new wxTimer(m_canvas);
     }
 }
@@ -2002,11 +2004,13 @@ GLCanvas3D::~GLCanvas3D()
         m_timer = nullptr;
     }
 
+#if !ENABLE_USE_UNIQUE_GLCONTEXT
     if (m_context != nullptr)
     {
         delete m_context;
         m_context = nullptr;
     }
+#endif // !ENABLE_USE_UNIQUE_GLCONTEXT
 }
 
 void GLCanvas3D::post_event(wxEvent &&event)
@@ -2096,6 +2100,7 @@ bool GLCanvas3D::init(bool useVBOs, bool use_legacy_opengl)
     return true;
 }
 
+#if !ENABLE_USE_UNIQUE_GLCONTEXT
 bool GLCanvas3D::set_current()
 {
     if ((m_canvas != nullptr) && (m_context != nullptr))
@@ -2103,6 +2108,7 @@ bool GLCanvas3D::set_current()
 
     return false;
 }
+#endif // !ENABLE_USE_UNIQUE_GLCONTEXT
 
 void GLCanvas3D::set_as_dirty()
 {
@@ -2118,9 +2124,11 @@ void GLCanvas3D::reset_volumes()
 {
     if (!m_volumes.empty())
     {
+#if !ENABLE_USE_UNIQUE_GLCONTEXT
         // ensures this canvas is current
         if (!set_current())
             return;
+#endif // !ENABLE_USE_UNIQUE_GLCONTEXT
 
         m_volumes.release_geometry();
         m_volumes.clear();
@@ -2515,7 +2523,11 @@ void GLCanvas3D::render()
         return;
 
     // ensures this canvas is current and initialized
+#if ENABLE_USE_UNIQUE_GLCONTEXT
+    if (!_set_current() || !_3DScene::init(m_canvas))
+#else
     if (!set_current() || !_3DScene::init(m_canvas))
+#endif // ENABLE_USE_UNIQUE_GLCONTEXT
         return;
 
     if (m_force_zoom_to_bed_enabled)
@@ -2620,9 +2632,11 @@ void GLCanvas3D::reload_scene(bool force)
 
     reset_volumes();
 
+#if !ENABLE_USE_UNIQUE_GLCONTEXT
     // ensures this canvas is current
     if (!set_current())
         return;
+#endif // !ENABLE_USE_UNIQUE_GLCONTEXT
 
     set_bed_shape(dynamic_cast<const ConfigOptionPoints*>(m_config->option("bed_shape"))->values);
 
@@ -2710,9 +2724,11 @@ void GLCanvas3D::load_gcode_preview(const GCodePreviewData& preview_data, const
 {
     if ((m_canvas != nullptr) && (m_print != nullptr))
     {
+#if !ENABLE_USE_UNIQUE_GLCONTEXT
         // ensures that this canvas is current
         if (!set_current())
             return;
+#endif // !ENABLE_USE_UNIQUE_GLCONTEXT
 
         if (m_volumes.empty())
         {
@@ -3504,8 +3520,10 @@ Point GLCanvas3D::get_local_mouse_position() const
 
 void GLCanvas3D::reset_legend_texture()
 {
+#if !ENABLE_USE_UNIQUE_GLCONTEXT
     if (!set_current())
         return;
+#endif // !ENABLE_USE_UNIQUE_GLCONTEXT
 
     m_legend_texture.reset();
 }
@@ -3651,13 +3669,27 @@ bool GLCanvas3D::_init_toolbar()
     return true;
 }
 
+#if ENABLE_USE_UNIQUE_GLCONTEXT
+bool GLCanvas3D::_set_current()
+{
+    if ((m_canvas != nullptr) && (m_context != nullptr))
+        return m_canvas->SetCurrent(*m_context);
+
+    return false;
+}
+#endif ENABLE_USE_UNIQUE_GLCONTEXT
+
 void GLCanvas3D::_resize(unsigned int w, unsigned int h)
 {
     if ((m_canvas == nullptr) && (m_context == nullptr))
         return;
 
     // ensures that this canvas is current
+#if ENABLE_USE_UNIQUE_GLCONTEXT
+    _set_current();
+#else
     set_current();
+#endif // ENABLE_USE_UNIQUE_GLCONTEXT
     ::glViewport(0, 0, w, h);
 
     ::glMatrixMode(GL_PROJECTION);
@@ -4316,9 +4348,11 @@ int GLCanvas3D::_get_first_selected_volume_id(int object_id) const
 
 void GLCanvas3D::_load_print_toolpaths()
 {
+#if !ENABLE_USE_UNIQUE_GLCONTEXT
     // ensures this canvas is current
     if (!set_current())
         return;
+#endif // !ENABLE_USE_UNIQUE_GLCONTEXT
 
     if (m_print == nullptr)
         return;
@@ -5428,24 +5462,30 @@ std::vector<float> GLCanvas3D::_parse_colors(const std::vector<std::string>& col
 
 void GLCanvas3D::_generate_legend_texture(const GCodePreviewData& preview_data, const std::vector<float>& tool_colors)
 {
+#if !ENABLE_USE_UNIQUE_GLCONTEXT
     if (!set_current())
         return;
+#endif // !ENABLE_USE_UNIQUE_GLCONTEXT
 
     m_legend_texture.generate(preview_data, tool_colors);
 }
 
 void GLCanvas3D::_generate_warning_texture(const std::string& msg)
 {
+#if !ENABLE_USE_UNIQUE_GLCONTEXT
     if (!set_current())
         return;
+#endif // !ENABLE_USE_UNIQUE_GLCONTEXT
 
     m_warning_texture.generate(msg);
 }
 
 void GLCanvas3D::_reset_warning_texture()
 {
+#if !ENABLE_USE_UNIQUE_GLCONTEXT
     if (!set_current())
         return;
+#endif // !ENABLE_USE_UNIQUE_GLCONTEXT
 
     m_warning_texture.reset();
 }
diff --git a/src/slic3r/GUI/GLCanvas3D.hpp b/src/slic3r/GUI/GLCanvas3D.hpp
index 04da72995..59893368e 100644
--- a/src/slic3r/GUI/GLCanvas3D.hpp
+++ b/src/slic3r/GUI/GLCanvas3D.hpp
@@ -552,11 +552,17 @@ public:
     GLCanvas3D(wxGLCanvas* canvas);
     ~GLCanvas3D();
 
-    wxGLCanvas* widget() { return m_canvas; }
+#if ENABLE_USE_UNIQUE_GLCONTEXT
+    void set_context(wxGLContext* context) { m_context = context; }
+#endif // ENABLE_USE_UNIQUE_GLCONTEXT
+
+    wxGLCanvas* get_wxglcanvas() { return m_canvas; }
 
     bool init(bool useVBOs, bool use_legacy_opengl);
 
+#if !ENABLE_USE_UNIQUE_GLCONTEXT
     bool set_current();
+#endif // !ENABLE_USE_UNIQUE_GLCONTEXT
 
     void set_as_dirty();
 
@@ -668,6 +674,9 @@ private:
 
     bool _init_toolbar();
 
+#if ENABLE_USE_UNIQUE_GLCONTEXT
+    bool _set_current();
+#endif // ENABLE_USE_UNIQUE_GLCONTEXT
     void _resize(unsigned int w, unsigned int h);
 
     BoundingBoxf3 _max_bounding_box() const;
diff --git a/src/slic3r/GUI/GLCanvas3DManager.cpp b/src/slic3r/GUI/GLCanvas3DManager.cpp
index 41f5ef22a..8720caba5 100644
--- a/src/slic3r/GUI/GLCanvas3DManager.cpp
+++ b/src/slic3r/GUI/GLCanvas3DManager.cpp
@@ -113,13 +113,29 @@ std::string GLCanvas3DManager::GLInfo::to_string(bool format_as_html, bool exten
 GLCanvas3DManager::EMultisampleState GLCanvas3DManager::s_multisample = GLCanvas3DManager::MS_Unknown;
 
 GLCanvas3DManager::GLCanvas3DManager()
+#if ENABLE_USE_UNIQUE_GLCONTEXT
+    : m_context(nullptr)
+    , m_current(nullptr)
+#else
     : m_current(nullptr)
+#endif // ENABLE_USE_UNIQUE_GLCONTEXT
     , m_gl_initialized(false)
     , m_use_legacy_opengl(false)
     , m_use_VBOs(false)
 {
 }
 
+#if ENABLE_USE_UNIQUE_GLCONTEXT
+GLCanvas3DManager::~GLCanvas3DManager()
+{
+    if (m_context != nullptr)
+    {
+        delete m_context;
+        m_context = nullptr;
+    }
+}
+#endif // ENABLE_USE_UNIQUE_GLCONTEXT
+
 bool GLCanvas3DManager::add(wxGLCanvas* canvas)
 {
     if (canvas == nullptr)
@@ -133,6 +149,18 @@ bool GLCanvas3DManager::add(wxGLCanvas* canvas)
         return false;
 
     canvas3D->bind_event_handlers();
+
+#if ENABLE_USE_UNIQUE_GLCONTEXT
+    if (m_context == nullptr)
+    {
+        m_context = new wxGLContext(canvas);
+        if (m_context == nullptr)
+            return false;
+    }
+
+    canvas3D->set_context(m_context);
+#endif // ENABLE_USE_UNIQUE_GLCONTEXT
+
     m_canvases.insert(CanvasesMap::value_type(canvas, canvas3D));
 
     return true;
diff --git a/src/slic3r/GUI/GLCanvas3DManager.hpp b/src/slic3r/GUI/GLCanvas3DManager.hpp
index 1a3036f9f..960bb6d2a 100644
--- a/src/slic3r/GUI/GLCanvas3DManager.hpp
+++ b/src/slic3r/GUI/GLCanvas3DManager.hpp
@@ -52,6 +52,9 @@ class GLCanvas3DManager
     typedef std::map<wxGLCanvas*, GLCanvas3D*> CanvasesMap;
 
     CanvasesMap m_canvases;
+#if ENABLE_USE_UNIQUE_GLCONTEXT
+    wxGLContext* m_context;
+#endif // ENABLE_USE_UNIQUE_GLCONTEXT
     wxGLCanvas* m_current;
     GLInfo m_gl_info;
     bool m_gl_initialized;
@@ -61,6 +64,9 @@ class GLCanvas3DManager
 
 public:
     GLCanvas3DManager();
+#if ENABLE_USE_UNIQUE_GLCONTEXT
+    ~GLCanvas3DManager();
+#endif // ENABLE_USE_UNIQUE_GLCONTEXT
 
     bool add(wxGLCanvas* canvas);
     bool remove(wxGLCanvas* canvas);
diff --git a/src/slic3r/GUI/GLToolbar.cpp b/src/slic3r/GUI/GLToolbar.cpp
index e1566e944..f2d882e22 100644
--- a/src/slic3r/GUI/GLToolbar.cpp
+++ b/src/slic3r/GUI/GLToolbar.cpp
@@ -339,13 +339,13 @@ void GLToolbar::do_action(unsigned int item_id)
                     item->set_state(GLToolbarItem::Hover);
 
                 m_parent.render();
-                item->do_action(m_parent.widget());
+                item->do_action(m_parent.get_wxglcanvas());
             }
             else
             {
                 item->set_state(GLToolbarItem::HoverPressed);
                 m_parent.render();
-                item->do_action(m_parent.widget());
+                item->do_action(m_parent.get_wxglcanvas());
                 if (item->get_state() != GLToolbarItem::Disabled)
                 {
                     // the item may get disabled during the action, if not, set it back to hover state
diff --git a/src/slic3r/GUI/GUI_Preview.hpp b/src/slic3r/GUI/GUI_Preview.hpp
index 7c7430c7c..ab7544ed8 100644
--- a/src/slic3r/GUI/GUI_Preview.hpp
+++ b/src/slic3r/GUI/GUI_Preview.hpp
@@ -53,7 +53,7 @@ public:
     Preview(wxNotebook* notebook, DynamicPrintConfig* config, Print* print, GCodePreviewData* gcode_preview_data);
     virtual ~Preview();
 
-    wxGLCanvas* get_canvas() { return m_canvas; }
+    wxGLCanvas* get_wxglcanvas() { return m_canvas; }
 
     void set_number_extruders(unsigned int number_extruders);
     void reset_gcode_preview_data();
diff --git a/src/slic3r/GUI/MainFrame.cpp b/src/slic3r/GUI/MainFrame.cpp
index 1c52d2155..e2a4f9d54 100644
--- a/src/slic3r/GUI/MainFrame.cpp
+++ b/src/slic3r/GUI/MainFrame.cpp
@@ -7,6 +7,7 @@
 #include <wx/menu.h>
 #include <wx/progdlg.h>
 #include <wx/tooltip.h>
+#include <wx/debug.h>
 
 #include "Tab.hpp"
 #include "PresetBundle.hpp"
@@ -154,40 +155,10 @@ void MainFrame::init_tabpanel()
 //             m_config->save(Slic3r::GUI::autosave) ;
 //     });
 
-    // The following event is emited by the C++ Tab implementation on preset selection,
+    // The following event is emited by Tab on preset selection,
     // or when the preset's "modified" status changes.
-//     EVT_COMMAND($self, -1, $PRESETS_CHANGED_EVENT, sub {
-//         my($self, $event) = @_;
-//         auto tab_name = event->GetString;
-// 
-//         Tab* tab = Slic3r::GUI::get_preset_tab(tab_name);
-//         if (m_plater) {
-//             // Update preset combo boxes(Print settings, Filament, Material, Printer) from their respective tabs.
-//             auto presets = tab->get_presets();
-//             if (presets){
-//                 auto reload_dependent_tabs = tab->get_dependent_tabs();
-//                 m_plater->update_presets(tab_name, reload_dependent_tabs, presets);
-//                 m_plater->{"selected_item_$tab_name"} = tab->get_selected_preset_item();
-//                 if (tab_name == "printer") {
-//                     // Printer selected at the Printer tab, update "compatible" marks at the print and filament selectors.
-//                     std::vector<std::string> tab_names_other = { "print", "filament", "sla_materialprinter" };
-//                     for (const auto tab_name_other : tab_names_other) {
-//                         Tab* cur_tab = m_options_tabs[tab_name_other];
-//                         // If the printer tells us that the print or filament preset has been switched or invalidated,
-//                         // refresh the print or filament tab page.Otherwise just refresh the combo box.
-//                         if (reload_dependent_tabs.empty() ||
-//                             find(reload_dependent_tabs.begin(), reload_dependent_tabs.end(), tab_name_other) ==
-//                             reload_dependent_tabs.end() )
-//                             cur_tab->update_tab_ui();
-//                         else
-//                             cur_tab->load_current_preset();
-//                             
-//                     }
-//                 }
-//                 m_plater->on_config_change(tab->get_config());
-//             }
-//         }
-//     });
+    Bind(EVT_TAB_PRESETS_CHANGED, &MainFrame::on_presets_changed, this);
+
 
     // The following event is emited by the C++ Tab implementation on object selection change.
 //     EVT_COMMAND($self, -1, $OBJECT_SELECTION_CHANGED_EVENT, sub {
@@ -793,6 +764,56 @@ wxMenuItem* MainFrame::append_menu_item(wxMenu* menu,
     return item;
 }
 
+void MainFrame::on_presets_changed(SimpleEvent &event)
+{
+    auto *tab = dynamic_cast<Tab*>(event.GetEventObject());
+    wxASSERT(tab != nullptr);
+    if (tab == nullptr) {
+        return;
+    }
+
+    // Update preset combo boxes(Print settings, Filament, Material, Printer) from their respective tabs.
+    auto presets = tab->get_presets();
+    if (presets) {
+        auto reload_dependent_tabs = tab->get_dependent_tabs();
+
+        // FIXME: The preset type really should be a property of Tab instead
+        Slic3r::Preset::Type preset_type;
+        if (tab == m_options_tabs["print"]) { preset_type = Slic3r::Preset::TYPE_PRINT; }
+        else if (tab == m_options_tabs["filament"]) { preset_type = Slic3r::Preset::TYPE_FILAMENT; }
+        else if (tab == m_options_tabs["sla_material"]) { preset_type = Slic3r::Preset::TYPE_SLA_MATERIAL; }
+        else if (tab == m_options_tabs["printer"]) { preset_type = Slic3r::Preset::TYPE_PRINTER; }
+        else {
+            wxASSERT(false);
+            return;
+        }
+
+        m_plater->sidebar().update_presets(preset_type);
+
+        // XXX: ???
+        // m_plater->{"selected_item_$tab_name"} = tab->get_selected_preset_item();
+
+        if (preset_type == Slic3r::Preset::TYPE_PRINTER) {
+            // Printer selected at the Printer tab, update "compatible" marks at the print and filament selectors.
+            // XXX: Do this in a more C++ way
+            std::vector<std::string> tab_names_other = { "print", "filament", "sla_material" };
+            for (const auto tab_name_other : tab_names_other) {
+                Tab* cur_tab = m_options_tabs[tab_name_other];
+                // If the printer tells us that the print or filament preset has been switched or invalidated,
+                // refresh the print or filament tab page.Otherwise just refresh the combo box.
+                if (reload_dependent_tabs.empty() ||
+                    find(reload_dependent_tabs.begin(), reload_dependent_tabs.end(), tab_name_other) ==
+                    reload_dependent_tabs.end() )
+                    cur_tab->update_tab_ui();
+                else
+                    cur_tab->load_current_preset();
+            }
+        }
+        // XXX: ?
+        // m_plater->on_config_change(tab->get_config());
+    }
+}
+
 // Called after the Preferences dialog is closed and the program settings are saved.
 // Update the UI based on the current preferences.
 void MainFrame::update_ui_from_settings()
diff --git a/src/slic3r/GUI/MainFrame.hpp b/src/slic3r/GUI/MainFrame.hpp
index 4063bd0c4..03b27a98b 100644
--- a/src/slic3r/GUI/MainFrame.hpp
+++ b/src/slic3r/GUI/MainFrame.hpp
@@ -9,6 +9,7 @@
 #include <map>
 
 #include "Plater.hpp"
+#include "Event.hpp"
 
 class wxMenuBar;
 class wxNotebook;
@@ -71,6 +72,7 @@ class MainFrame : public wxFrame
     std::string     get_base_name(const wxString full_name) const ;
     std::string     get_dir_name(const wxString full_name) const ;
 
+    void on_presets_changed(SimpleEvent&);
     Tab*         get_tab(const std::string& name);
 
 public:
diff --git a/src/slic3r/GUI/Plater.cpp b/src/slic3r/GUI/Plater.cpp
index 522dfb471..d76a0ca1b 100644
--- a/src/slic3r/GUI/Plater.cpp
+++ b/src/slic3r/GUI/Plater.cpp
@@ -463,38 +463,37 @@ Sidebar::~Sidebar() {}
 
 void Sidebar::update_presets(Preset::Type preset_type)
 {
-    // TODO: wxApp access
-
     switch (preset_type) {
     case Preset::TYPE_FILAMENT:
-        // my $choice_idx = 0;
         if (p->combos_filament.size() == 1) {
             // Single filament printer, synchronize the filament presets.
-            // wxTheApp->{preset_bundle}->set_filament_preset(0, wxTheApp->{preset_bundle}->filament->get_selected_preset->name);
+            const std::string &name = wxGetApp().preset_bundle->filaments.get_selected_preset().name;
+            wxGetApp().preset_bundle->set_filament_preset(0, name);
         }
 
         for (size_t i = 0; i < p->combos_filament.size(); i++) {
-            // wxTheApp->{preset_bundle}->update_platter_filament_ui($choice_idx, $choice);
+            wxGetApp().preset_bundle->update_platter_filament_ui(i, p->combos_filament[i]);
         }
+
         break;
 
     case Preset::TYPE_PRINT:
-        // wxTheApp->{preset_bundle}->print->update_platter_ui($choosers[0]);
+        wxGetApp().preset_bundle->prints.update_platter_ui(p->combo_print);
         break;
 
     case Preset::TYPE_SLA_MATERIAL:
-        // wxTheApp->{preset_bundle}->sla_material->update_platter_ui($choosers[0]);
+        wxGetApp().preset_bundle->sla_materials.update_platter_ui(p->combo_sla_material);
         break;
 
     case Preset::TYPE_PRINTER:
         // Update the print choosers to only contain the compatible presets, update the dirty flags.
-        // wxTheApp->{preset_bundle}->print->update_platter_ui($self->{preset_choosers}{print}->[0]);
+        wxGetApp().preset_bundle->prints.update_platter_ui(p->combo_print);
         // Update the printer choosers, update the dirty flags.
-        // wxTheApp->{preset_bundle}->printer->update_platter_ui($choosers[0]);
+        wxGetApp().preset_bundle->printers.update_platter_ui(p->combo_printer);
         // Update the filament choosers to only contain the compatible presets, update the color preview,
         // update the dirty flags.
         for (size_t i = 0; i < p->combos_filament.size(); i++) {
-            // wxTheApp->{preset_bundle}->update_platter_filament_ui($choice_idx, $choice);
+            wxGetApp().preset_bundle->update_platter_filament_ui(i, p->combos_filament[i]);
         }
         break;
 
@@ -502,7 +501,7 @@ void Sidebar::update_presets(Preset::Type preset_type)
     }
 
     // Synchronize config.ini with the current selections.
-    // wxTheApp->{preset_bundle}->export_selections(wxTheApp->{app_config});
+    wxGetApp().preset_bundle->export_selections(*wxGetApp().app_config);
 }
 
 ObjectManipulation* Sidebar::obj_manipul()
@@ -623,7 +622,8 @@ struct Plater::priv
     void update_ui_from_settings();
     ProgressStatusBar* statusbar();
     std::string get_config(const std::string &key) const;
-    BoundingBox bed_shape_bb() const;
+    BoundingBoxf bed_shape_bb() const;
+    BoundingBox scaled_bed_shape_bb() const;
     std::vector<size_t> load_files(const std::vector<fs::path> &input_files);
     std::vector<size_t> load_model_objects(const ModelObjectPtrs &model_objects);
 
@@ -723,7 +723,7 @@ Plater::priv::priv(Plater *q, MainFrame *main_frame) :
     canvas3D->Bind(EVT_GLTOOLBAR_ADD, &priv::on_action_add, this);
     canvas3D->Bind(EVT_GLCANVAS_VIEWPORT_CHANGED, &priv::on_viewport_changed, this);
 
-    preview->get_canvas()->Bind(EVT_GLCANVAS_VIEWPORT_CHANGED, &priv::on_viewport_changed, this);
+    preview->get_wxglcanvas()->Bind(EVT_GLCANVAS_VIEWPORT_CHANGED, &priv::on_viewport_changed, this);
 
     q->Bind(EVT_SLICING_COMPLETED, &priv::on_update_print_preview, this);
     q->Bind(EVT_PROCESS_COMPLETED, &priv::on_process_completed, this);
@@ -751,7 +751,7 @@ void Plater::priv::update(bool force_autocenter)
         // auto *bed_shape_opt = config->opt<ConfigOptionPoints>("bed_shape");
         // const auto bed_shape = Slic3r::Polygon::new_scale(bed_shape_opt->values);
         // const BoundingBox bed_shape_bb = bed_shape.bounding_box();
-        const Vec2d bed_center = bed_shape_bb().center().cast<double>();
+        const Vec2d& bed_center = bed_shape_bb().center();
         model.center_instances_around_point(bed_center);
     }
 
@@ -787,7 +787,13 @@ std::string Plater::priv::get_config(const std::string &key) const
     return wxGetApp().app_config->get(key);
 }
 
-BoundingBox Plater::priv::bed_shape_bb() const
+BoundingBoxf Plater::priv::bed_shape_bb() const
+{
+    BoundingBox bb = scaled_bed_shape_bb();
+    return BoundingBoxf(unscale(bb.min), unscale(bb.max));
+}
+
+BoundingBox Plater::priv::scaled_bed_shape_bb() const
 {
     const auto *bed_shape_opt = config->opt<ConfigOptionPoints>("bed_shape");
     const auto bed_shape = Slic3r::Polygon::new_scale(bed_shape_opt->values);
@@ -914,7 +920,7 @@ Vec3crd to_3d(const Point &p, coord_t z) { return Vec3crd(p(0), p(1), z); }
 
 std::vector<size_t>  Plater::priv::load_model_objects(const ModelObjectPtrs &model_objects)
 {
-    const BoundingBox bed_shape = bed_shape_bb();
+    const BoundingBoxf bed_shape = bed_shape_bb();
     const Vec3d bed_center = to_3d(bed_shape.center().cast<double>(), 0.0);
     const Vec3d bed_size = to_3d(bed_shape.size().cast<double>(), 1.0);
 
@@ -1069,7 +1075,7 @@ void Plater::priv::on_action_add(SimpleEvent&)
 void Plater::priv::on_viewport_changed(SimpleEvent& evt)
 {
     wxObject* o = evt.GetEventObject();
-    if (o == preview->get_canvas())
+    if (o == preview->get_wxglcanvas())
         preview->set_viewport_into_scene(canvas3D);
     else if (o == canvas3D)
         preview->set_viewport_from_scene(canvas3D);
diff --git a/src/slic3r/GUI/Tab.cpp b/src/slic3r/GUI/Tab.cpp
index 1e39e2a70..6b0b89eee 100644
--- a/src/slic3r/GUI/Tab.cpp
+++ b/src/slic3r/GUI/Tab.cpp
@@ -33,6 +33,12 @@
 namespace Slic3r {
 namespace GUI {
 
+
+wxDEFINE_EVENT(EVT_TAB_VALUE_CHANGED, wxCommandEvent);
+wxDEFINE_EVENT(EVT_TAB_PRESETS_CHANGED, SimpleEvent);
+
+
+// sub new
 void Tab::create_preset_tab()
 {
     m_preset_bundle = wxGetApp().preset_bundle;
@@ -659,31 +665,28 @@ void Tab::load_key_value(const std::string& opt_key, const boost::any& value, bo
 	update();
 }
 
-// extern wxFrame *g_wxMainFrame; // #ys_FIXME
-
 void Tab::on_value_change(const std::string& opt_key, const boost::any& value)
 {
-	if (m_event_value_change > 0) {
-		wxCommandEvent event(m_event_value_change);
-		std::string str_out = opt_key + " " + m_name;
-		event.SetString(str_out);
-		if (opt_key == "extruders_count")
-		{
-			int val = boost::any_cast<size_t>(value);
-			event.SetInt(val);
-		}
-
-        if (opt_key == "printer_technology")
-        {
-            int val = boost::any_cast<PrinterTechnology>(value);
-            event.SetInt(val);
-//             g_wxMainFrame->ProcessWindowEvent(event);// #ys_FIXME
-            return;
-        }
-        
-// 		g_wxMainFrame->ProcessWindowEvent(event);// #ys_FIXME
+	wxCommandEvent event(EVT_TAB_VALUE_CHANGED);
+	event.SetEventObject(this);
+	event.SetString(opt_key);
+	if (opt_key == "extruders_count")
+	{
+		int val = boost::any_cast<size_t>(value);
+		event.SetInt(val);
 	}
 
+    if (opt_key == "printer_technology")
+    {
+        int val = boost::any_cast<PrinterTechnology>(value);
+        event.SetInt(val);
+        wxPostEvent(this, event);
+        return;
+    }
+
+	wxPostEvent(this, event);
+
+
     auto og_freq_chng_params = wxGetApp().sidebar().og_freq_chng_params();
 	if (opt_key == "fill_density")
 	{
@@ -736,11 +739,9 @@ void Tab::update_wiping_button_visibility() {
 // to uddate number of "filament" selection boxes when the number of extruders change.
 void Tab::on_presets_changed()
 {
-	if (m_event_presets_changed > 0) {
-		wxCommandEvent event(m_event_presets_changed);
-		event.SetString(m_name);
-// 		g_wxMainFrame->ProcessWindowEvent(event); // #ys_FIXME
-	}
+	wxCommandEvent event(EVT_TAB_PRESETS_CHANGED);
+	event.SetEventObject(this);
+	wxPostEvent(this, event);
 	update_preset_description_line();
 }
 
diff --git a/src/slic3r/GUI/Tab.hpp b/src/slic3r/GUI/Tab.hpp
index c9fb1764c..4c7f32e7e 100644
--- a/src/slic3r/GUI/Tab.hpp
+++ b/src/slic3r/GUI/Tab.hpp
@@ -25,14 +25,15 @@
 #include <wx/imaglist.h>
 #include <wx/statbox.h>
 #include <wx/dataview.h>
+#include <wx/event.h>
 
 #include <map>
 #include <vector>
 #include <memory>
 
 #include "BedShapeDialog.hpp"
+#include "Event.hpp"
 
-//!enum { ID_TAB_TREE = wxID_HIGHEST + 1 };
 
 namespace Slic3r {
 namespace GUI {
@@ -96,7 +97,10 @@ protected:
 	const wxColour*		m_item_color;
 };
 
-// Slic3r::GUI::Tab;
+
+wxDECLARE_EVENT(EVT_TAB_VALUE_CHANGED, wxCommandEvent);
+wxDECLARE_EVENT(EVT_TAB_PRESETS_CHANGED, SimpleEvent);
+
 
 using PageShp = std::shared_ptr<Page>;
 class Tab: public wxPanel
@@ -178,10 +182,6 @@ protected:
 
 	t_icon_descriptions	m_icon_descriptions = {};
 
-	// The two following two event IDs are generated at Plater.pm by calling Wx::NewEventType.
-	wxEventType			m_event_value_change = 0;
-	wxEventType 		m_event_presets_changed = 0;
-
 	bool				m_is_modified_values{ false };
 	bool				m_is_nonsys_values{ true };
 	bool				m_postpone_update_ui {false};
@@ -211,10 +211,6 @@ public:
 	wxString	title()	 const { return m_title; }
 	std::string	name()	 const { return m_name; }
 
-	// Set the events to the callbacks posted to the main frame window (currently implemented in Perl).
-	void 		set_event_value_change(wxEventType evt) { m_event_value_change = evt; }
-	void 		set_event_presets_changed(wxEventType evt) { m_event_presets_changed = evt; }
-	
 	void		create_preset_tab();
 	void		load_current_preset();
 	void        rebuild_page_tree(bool tree_sel_change_event = false);