diff --git a/lib/Slic3r/GUI/Plater.pm b/lib/Slic3r/GUI/Plater.pm
index 96bddd466..2b0a5a0d5 100644
--- a/lib/Slic3r/GUI/Plater.pm
+++ b/lib/Slic3r/GUI/Plater.pm
@@ -186,7 +186,6 @@ sub new {
     # Initialize 3D toolpaths preview
     if ($Slic3r::GUI::have_OpenGL) {
         $self->{preview3D} = Slic3r::GUI::Plater::3DPreview->new($self->{preview_notebook}, $self->{print}, $self->{gcode_preview_data}, $self->{config});
-        Slic3r::GUI::_3DScene::set_active($self->{preview3D}->canvas, 0);
         Slic3r::GUI::_3DScene::enable_legend_texture($self->{preview3D}->canvas, 1);
         Slic3r::GUI::_3DScene::register_on_viewport_changed_callback($self->{preview3D}->canvas, sub { Slic3r::GUI::_3DScene::set_viewport_from_scene($self->{canvas3D}, $self->{preview3D}->canvas); });
         $self->{preview_notebook}->AddPage($self->{preview3D}, L('Preview'));
@@ -202,19 +201,12 @@ sub new {
     EVT_NOTEBOOK_PAGE_CHANGED($self, $self->{preview_notebook}, sub {
         my $preview = $self->{preview_notebook}->GetCurrentPage;
         if (($preview != $self->{preview3D}) && ($preview != $self->{canvas3D})) {
-            Slic3r::GUI::_3DScene::set_active($self->{preview3D}->canvas, 0);
-            Slic3r::GUI::_3DScene::set_active($self->{canvas3D}, 0);
-            Slic3r::GUI::_3DScene::reset_current_canvas();
             $preview->OnActivate if $preview->can('OnActivate');        
         } elsif ($preview == $self->{preview3D}) {
-            Slic3r::GUI::_3DScene::set_active($self->{preview3D}->canvas, 1);
-            Slic3r::GUI::_3DScene::set_active($self->{canvas3D}, 0);
             $self->{preview3D}->load_print;
             # sets the canvas as dirty to force a render at the 1st idle event (wxWidgets IsShownOnScreen() is buggy and cannot be used reliably)
             Slic3r::GUI::_3DScene::set_as_dirty($self->{preview3D}->canvas);
         } elsif ($preview == $self->{canvas3D}) {
-            Slic3r::GUI::_3DScene::set_active($self->{canvas3D}, 1);
-            Slic3r::GUI::_3DScene::set_active($self->{preview3D}->canvas, 0);
             if (Slic3r::GUI::_3DScene::is_reload_delayed($self->{canvas3D})) {
                 my $selections = $self->collect_selections;
                 Slic3r::GUI::_3DScene::set_objects_selections($self->{canvas3D}, \@$selections);
diff --git a/lib/Slic3r/GUI/Plater/3DPreview.pm b/lib/Slic3r/GUI/Plater/3DPreview.pm
index c7dab869f..9ed2374ec 100644
--- a/lib/Slic3r/GUI/Plater/3DPreview.pm
+++ b/lib/Slic3r/GUI/Plater/3DPreview.pm
@@ -279,7 +279,6 @@ sub reload_print {
     my ($self, $force) = @_;
 
     Slic3r::GUI::_3DScene::reset_volumes($self->canvas);
-    Slic3r::GUI::_3DScene::reset_current_canvas();            
     $self->_loaded(0);
 
     if (! $self->IsShown && ! $force) {
diff --git a/xs/src/slic3r/GUI/3DScene.cpp b/xs/src/slic3r/GUI/3DScene.cpp
index a499825a4..09e10ac28 100644
--- a/xs/src/slic3r/GUI/3DScene.cpp
+++ b/xs/src/slic3r/GUI/3DScene.cpp
@@ -1754,21 +1754,6 @@ bool _3DScene::init(wxGLCanvas* canvas)
     return s_canvas_mgr.init(canvas);
 }
 
-bool _3DScene::set_current(wxGLCanvas* canvas, bool force)
-{
-    return s_canvas_mgr.set_current(canvas, force);
-}
-
-void _3DScene::reset_current_canvas()
-{
-    s_canvas_mgr.set_current(nullptr, false);
-}
-
-void _3DScene::set_active(wxGLCanvas* canvas, bool active)
-{
-    s_canvas_mgr.set_active(canvas, active);
-}
-
 void _3DScene::set_as_dirty(wxGLCanvas* canvas)
 {
     s_canvas_mgr.set_as_dirty(canvas);
diff --git a/xs/src/slic3r/GUI/3DScene.hpp b/xs/src/slic3r/GUI/3DScene.hpp
index f45bab276..9016f984d 100644
--- a/xs/src/slic3r/GUI/3DScene.hpp
+++ b/xs/src/slic3r/GUI/3DScene.hpp
@@ -516,10 +516,6 @@ public:
 
     static bool init(wxGLCanvas* canvas);
 
-    static bool set_current(wxGLCanvas* canvas, bool force);
-    static void reset_current_canvas();
-
-    static void set_active(wxGLCanvas* canvas, bool active);
     static void set_as_dirty(wxGLCanvas* canvas);
 
     static unsigned int get_volumes_count(wxGLCanvas* canvas);
diff --git a/xs/src/slic3r/GUI/ConfigWizard.cpp b/xs/src/slic3r/GUI/ConfigWizard.cpp
index ce06da853..642c6dce7 100644
--- a/xs/src/slic3r/GUI/ConfigWizard.cpp
+++ b/xs/src/slic3r/GUI/ConfigWizard.cpp
@@ -83,8 +83,11 @@ PrinterPicker::PrinterPicker(wxWindow *parent, const VendorProfile &vendor, cons
 
 		const auto model_id = model.id;
 
+		bool default_variant = true;   // Mark the first variant as default in the GUI
 		for (const auto &variant : model.variants) {
-			const auto label = wxString::Format("%s %s %s", variant.name, _(L("mm")), _(L("nozzle")));
+			const auto label = wxString::Format("%s %s %s %s", variant.name, _(L("mm")), _(L("nozzle")),
+				(default_variant ? _(L("(default)")) : wxString()));
+			default_variant = false;
 			auto *cbox = new Checkbox(panel, label, model_id, variant.name);
 			const size_t idx = cboxes.size();
 			cboxes.push_back(cbox);
@@ -113,11 +116,6 @@ PrinterPicker::PrinterPicker(wxWindow *parent, const VendorProfile &vendor, cons
 	sizer->Add(all_none_sizer, 0, wxEXPAND);
 
 	SetSizer(sizer);
-
-	if (cboxes.size() > 0) {
-		cboxes[0]->SetValue(true);
-		on_checkbox(cboxes[0], true);
-	}
 }
 
 void PrinterPicker::select_all(bool select)
@@ -130,6 +128,14 @@ void PrinterPicker::select_all(bool select)
 	}
 }
 
+void PrinterPicker::select_one(size_t i, bool select)
+{
+	if (i < cboxes.size() && cboxes[i]->GetValue() != select) {
+		cboxes[i]->SetValue(select);
+		on_checkbox(cboxes[i], select);
+	}
+}
+
 void PrinterPicker::on_checkbox(const Checkbox *cbox, bool checked)
 {
 	variants_checked += checked ? 1 : -1;
@@ -232,6 +238,7 @@ PageWelcome::PageWelcome(ConfigWizard *parent) :
 		AppConfig &appconfig_vendors = this->wizard_p()->appconfig_vendors;
 
 		printer_picker = new PrinterPicker(this, vendor_prusa->second, appconfig_vendors);
+		printer_picker->select_one(0, true);    // Select the default (first) model/variant on the Prusa vendor
 		printer_picker->Bind(EVT_PRINTER_PICK, [this, &appconfig_vendors](const PrinterPickerEvent &evt) {
 			appconfig_vendors.set_variant(evt.vendor_id, evt.model_id, evt.variant_name, evt.enable);
 			this->on_variant_checked();
diff --git a/xs/src/slic3r/GUI/ConfigWizard_private.hpp b/xs/src/slic3r/GUI/ConfigWizard_private.hpp
index 72cb88655..04319a1b4 100644
--- a/xs/src/slic3r/GUI/ConfigWizard_private.hpp
+++ b/xs/src/slic3r/GUI/ConfigWizard_private.hpp
@@ -56,6 +56,7 @@ struct PrinterPicker: wxPanel
 	PrinterPicker(wxWindow *parent, const VendorProfile &vendor, const AppConfig &appconfig_vendors);
 
 	void select_all(bool select);
+	void select_one(size_t i, bool select);
 	void on_checkbox(const Checkbox *cbox, bool checked);
 };
 
diff --git a/xs/src/slic3r/GUI/GLCanvas3D.cpp b/xs/src/slic3r/GUI/GLCanvas3D.cpp
index 2148579e8..adea27fa4 100644
--- a/xs/src/slic3r/GUI/GLCanvas3D.cpp
+++ b/xs/src/slic3r/GUI/GLCanvas3D.cpp
@@ -1408,15 +1408,14 @@ GLGizmoBase* GLCanvas3D::Gizmos::_get_current() const
     return (it != m_gizmos.end()) ? it->second : nullptr;
 }
 
-GLCanvas3D::GLCanvas3D(wxGLCanvas* canvas, wxGLContext* context)
+GLCanvas3D::GLCanvas3D(wxGLCanvas* canvas)
     : m_canvas(canvas)
-    , m_context(context)
+    , m_context(nullptr)
     , m_timer(nullptr)
     , m_config(nullptr)
     , m_print(nullptr)
     , m_model(nullptr)
     , m_dirty(true)
-    , m_active(true)
     , m_initialized(false)
     , m_use_VBOs(false)
     , m_force_zoom_to_bed_enabled(false)
@@ -1434,7 +1433,10 @@ GLCanvas3D::GLCanvas3D(wxGLCanvas* canvas, wxGLContext* context)
     , m_reload_delayed(false)
 {
     if (m_canvas != nullptr)
+    {
+        m_context = new wxGLContext(m_canvas);
         m_timer = new wxTimer(m_canvas);
+    }
 }
 
 GLCanvas3D::~GLCanvas3D()
@@ -1447,6 +1449,12 @@ GLCanvas3D::~GLCanvas3D()
         m_timer = nullptr;
     }
 
+    if (m_context != nullptr)
+    {
+        delete m_context;
+        m_context = nullptr;
+    }
+
     _deregister_callbacks();
 }
 
@@ -1455,6 +1463,9 @@ bool GLCanvas3D::init(bool useVBOs, bool use_legacy_opengl)
     if (m_initialized)
         return true;
 
+    if ((m_canvas == nullptr) || (m_context == nullptr))
+        return false;
+
     ::glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
     ::glClearDepth(1.0f);
 
@@ -1520,19 +1531,14 @@ bool GLCanvas3D::init(bool useVBOs, bool use_legacy_opengl)
     return true;
 }
 
-bool GLCanvas3D::set_current(bool force)
+bool GLCanvas3D::set_current()
 {
-    if ((force || m_active) && (m_canvas != nullptr) && (m_context != nullptr))
+    if ((m_canvas != nullptr) && (m_context != nullptr))
         return m_canvas->SetCurrent(*m_context);
 
     return false;
 }
 
-void GLCanvas3D::set_active(bool active)
-{
-    m_active = active;
-}
-
 void GLCanvas3D::set_as_dirty()
 {
     m_dirty = true;
@@ -1549,7 +1555,7 @@ void GLCanvas3D::reset_volumes()
     if (!m_volumes.empty())
     {
         // ensures this canvas is current
-        if ((m_canvas == nullptr) || !_3DScene::set_current(m_canvas, true))
+        if (!set_current())
             return;
 
         m_volumes.release_geometry();
@@ -1655,6 +1661,8 @@ void GLCanvas3D::set_bed_shape(const Pointfs& shape)
     // Set the origin and size for painting of the coordinate system axes.
     m_axes.origin = Pointf3(0.0, 0.0, (coordf_t)GROUND_Z);
     set_axes_length(0.3f * (float)m_bed.get_bounding_box().max_size());
+
+    m_dirty = true;
 }
 
 void GLCanvas3D::set_auto_bed_shape()
@@ -1850,7 +1858,7 @@ void GLCanvas3D::render()
         return;
 
     // ensures this canvas is current and initialized
-    if (!_3DScene::set_current(m_canvas, false) || !_3DScene::init(m_canvas))
+    if (!set_current() || !_3DScene::init(m_canvas))
         return;
 
     if (m_force_zoom_to_bed_enabled)
@@ -1933,7 +1941,7 @@ void GLCanvas3D::reload_scene(bool force)
     reset_volumes();
 
     // ensures this canvas is current
-    if (!_3DScene::set_current(m_canvas, true))
+    if (!set_current())
         return;
 
     set_bed_shape(dynamic_cast<const ConfigOptionPoints*>(m_config->option("bed_shape"))->values);
@@ -2008,7 +2016,7 @@ void GLCanvas3D::reload_scene(bool force)
 void GLCanvas3D::load_print_toolpaths()
 {
     // ensures this canvas is current
-    if (!_3DScene::set_current(m_canvas, true))
+    if (!set_current())
         return;
 
     if (m_print == nullptr)
@@ -2376,7 +2384,7 @@ void GLCanvas3D::load_gcode_preview(const GCodePreviewData& preview_data, const
     if ((m_canvas != nullptr) && (m_print != nullptr))
     {
         // ensures that this canvas is current
-        if (!_3DScene::set_current(m_canvas, true))
+        if (!set_current())
             return;
 
         if (m_volumes.empty())
@@ -2693,11 +2701,7 @@ void GLCanvas3D::on_mouse(wxMouseEvent& evt)
 #endif
     } 
     else if (evt.LeftDClick() && (m_hover_volume_id != -1))
-    {
-        m_active = false;
         m_on_double_click_callback.call();
-        m_active = true;
-    }
     else if (evt.LeftDown() || evt.RightDown())
     {
         // If user pressed left or right button we first check whether this happened
@@ -2793,11 +2797,7 @@ void GLCanvas3D::on_mouse(wxMouseEvent& evt)
                 {
                     // if right clicking on volume, propagate event through callback
                     if (m_volumes.volumes[volume_idx]->hover)
-                    {
-                        m_active = false;
                         m_on_right_click_callback.call(pos.x, pos.y);
-                        m_active = true;
-                    }
                 }
             }
         }
@@ -3004,7 +3004,7 @@ Point GLCanvas3D::get_local_mouse_position() const
 
 bool GLCanvas3D::_is_shown_on_screen() const
 {
-    return (m_canvas != nullptr) ? m_active && m_canvas->IsShownOnScreen() : false;
+    return (m_canvas != nullptr) ? m_canvas->IsShownOnScreen() : false;
 }
 
 void GLCanvas3D::_force_zoom_to_bed()
@@ -3019,7 +3019,7 @@ void GLCanvas3D::_resize(unsigned int w, unsigned int h)
         return;
 
     // ensures that this canvas is current
-    _3DScene::set_current(m_canvas, false);
+    set_current();
     ::glViewport(0, 0, w, h);
 
     ::glMatrixMode(GL_PROJECTION);
diff --git a/xs/src/slic3r/GUI/GLCanvas3D.hpp b/xs/src/slic3r/GUI/GLCanvas3D.hpp
index 237044e83..b0706a05d 100644
--- a/xs/src/slic3r/GUI/GLCanvas3D.hpp
+++ b/xs/src/slic3r/GUI/GLCanvas3D.hpp
@@ -401,9 +401,6 @@ private:
     Model* m_model;
 
     bool m_dirty;
-    // the active member has been introduced to overcome a bug in wxWidgets method IsShownOnScreen() which always return true
-    // when a window is inside a wxNotebook
-    bool m_active;
     bool m_initialized;
     bool m_use_VBOs;
     bool m_force_zoom_to_bed_enabled;
@@ -444,14 +441,13 @@ private:
     PerlCallback m_on_gizmo_scale_uniformly_callback;
 
 public:
-    GLCanvas3D(wxGLCanvas* canvas, wxGLContext* context);
+    GLCanvas3D(wxGLCanvas* canvas);
     ~GLCanvas3D();
 
     bool init(bool useVBOs, bool use_legacy_opengl);
 
-    bool set_current(bool force);
+    bool set_current();
 
-    void set_active(bool active);
     void set_as_dirty();
 
     unsigned int get_volumes_count() const;
diff --git a/xs/src/slic3r/GUI/GLCanvas3DManager.cpp b/xs/src/slic3r/GUI/GLCanvas3DManager.cpp
index 62d17827a..f817e7739 100644
--- a/xs/src/slic3r/GUI/GLCanvas3DManager.cpp
+++ b/xs/src/slic3r/GUI/GLCanvas3DManager.cpp
@@ -114,20 +114,13 @@ std::string GLCanvas3DManager::GLInfo::to_string(bool format_as_html, bool exten
 }
 
 GLCanvas3DManager::GLCanvas3DManager()
-    : m_context(nullptr)
-    , m_current(nullptr)
+    : m_current(nullptr)
     , m_gl_initialized(false)
     , m_use_legacy_opengl(false)
     , m_use_VBOs(false)
 {
 }
 
-GLCanvas3DManager::~GLCanvas3DManager()
-{
-    if (m_context != nullptr)
-        delete m_context;
-}
-
 bool GLCanvas3DManager::add(wxGLCanvas* canvas)
 {
     if (canvas == nullptr)
@@ -136,14 +129,7 @@ bool GLCanvas3DManager::add(wxGLCanvas* canvas)
     if (_get_canvas(canvas) != m_canvases.end())
         return false;
 
-    if (m_context == nullptr)
-    {
-        m_context = new wxGLContext(canvas);
-        if (m_context == nullptr)
-            return false;
-    }
-
-    GLCanvas3D* canvas3D = new GLCanvas3D(canvas, m_context);
+    GLCanvas3D* canvas3D = new GLCanvas3D(canvas);
     if (canvas3D == nullptr)
         return false;
 
@@ -213,41 +199,6 @@ bool GLCanvas3DManager::init(wxGLCanvas* canvas)
         return false;
 }
 
-bool GLCanvas3DManager::set_current(wxGLCanvas* canvas, bool force)
-{
-    // given canvas is already current, return
-    if (m_current == canvas)
-        return true;
-
-    if (canvas == nullptr)
-    {
-        m_current = nullptr;
-        return true;
-    }
-
-    // set given canvas as current
-    CanvasesMap::iterator it = _get_canvas(canvas);
-    if (it != m_canvases.end())
-    {
-        bool res = it->second->set_current(force);
-        if (res)
-        {
-            m_current = canvas;
-            return true;
-        }
-    }
-
-    m_current = nullptr;
-    return false;
-}
-
-void GLCanvas3DManager::set_active(wxGLCanvas* canvas, bool active)
-{
-    CanvasesMap::iterator it = _get_canvas(canvas);
-    if (it != m_canvases.end())
-        it->second->set_active(active);
-}
-
 void GLCanvas3DManager::set_as_dirty(wxGLCanvas* canvas)
 {
     CanvasesMap::iterator it = _get_canvas(canvas);
diff --git a/xs/src/slic3r/GUI/GLCanvas3DManager.hpp b/xs/src/slic3r/GUI/GLCanvas3DManager.hpp
index 35a1db206..9d9285601 100644
--- a/xs/src/slic3r/GUI/GLCanvas3DManager.hpp
+++ b/xs/src/slic3r/GUI/GLCanvas3DManager.hpp
@@ -43,7 +43,6 @@ class GLCanvas3DManager
 
     typedef std::map<wxGLCanvas*, GLCanvas3D*> CanvasesMap;
 
-    wxGLContext* m_context;
     CanvasesMap m_canvases;
     wxGLCanvas* m_current;
     GLInfo m_gl_info;
@@ -53,7 +52,6 @@ class GLCanvas3DManager
 
 public:
     GLCanvas3DManager();
-    ~GLCanvas3DManager();
 
     bool add(wxGLCanvas* canvas);
     bool remove(wxGLCanvas* canvas);
@@ -70,8 +68,6 @@ public:
 
     bool init(wxGLCanvas* canvas);
 
-    bool set_current(wxGLCanvas* canvas, bool force);
-    void set_active(wxGLCanvas* canvas, bool active);
     void set_as_dirty(wxGLCanvas* canvas);
 
     unsigned int get_volumes_count(wxGLCanvas* canvas) const;
diff --git a/xs/src/slic3r/Utils/Http.cpp b/xs/src/slic3r/Utils/Http.cpp
index 47021d39f..949a0e7d6 100644
--- a/xs/src/slic3r/Utils/Http.cpp
+++ b/xs/src/slic3r/Utils/Http.cpp
@@ -71,6 +71,7 @@ Http::priv::priv(const std::string &url) :
 	form(nullptr),
 	form_end(nullptr),
 	headerlist(nullptr),
+	limit(0),
 	cancel(false)
 {
 	if (curl == nullptr) {
diff --git a/xs/src/slic3r/Utils/Http.hpp b/xs/src/slic3r/Utils/Http.hpp
index 73656bf88..7c2bd84fc 100644
--- a/xs/src/slic3r/Utils/Http.hpp
+++ b/xs/src/slic3r/Utils/Http.hpp
@@ -46,7 +46,8 @@ public:
 	Http& operator=(const Http &) = delete;
 	Http& operator=(Http &&) = delete;
 
-	// Sets a maximum size of the data that can be received. The default is 5MB.
+	// Sets a maximum size of the data that can be received.
+	// A value of zero sets the default limit, which is is 5MB.
 	Http& size_limit(size_t sizeLimit);
 	// Sets a HTTP header field.
 	Http& header(std::string name, const std::string &value);
diff --git a/xs/src/slic3r/Utils/PresetUpdater.cpp b/xs/src/slic3r/Utils/PresetUpdater.cpp
index 8159a75e2..1ce814b89 100644
--- a/xs/src/slic3r/Utils/PresetUpdater.cpp
+++ b/xs/src/slic3r/Utils/PresetUpdater.cpp
@@ -537,15 +537,15 @@ bool PresetUpdater::config_update() const
 			incompats_map.emplace(std::make_pair(std::move(vendor), std::move(restrictions)));
 		}
 
+		p->had_config_update = true;   // This needs to be done before a dialog is shown because of OnIdle() + CallAfter() in Perl
+
 		GUI::MsgDataIncompatible dlg(std::move(incompats_map));
 		const auto res = dlg.ShowModal();
 		if (res == wxID_REPLACE) {
 			BOOST_LOG_TRIVIAL(info) << "User wants to re-configure...";
 			p->perform_updates(std::move(updates));
 			GUI::ConfigWizard wizard(nullptr, GUI::ConfigWizard::RR_DATA_INCOMPAT);
-			if (wizard.run(GUI::get_preset_bundle(), this)) {
-				p->had_config_update = true;
-			} else {
+			if (! wizard.run(GUI::get_preset_bundle(), this)) {	
 				return false;
 			}
 		} else {
@@ -566,6 +566,8 @@ bool PresetUpdater::config_update() const
 			updates_map.emplace(std::make_pair(std::move(vendor), std::move(ver_str)));
 		}
 
+		p->had_config_update = true;   // Ditto, see above
+
 		GUI::MsgUpdateConfig dlg(std::move(updates_map));
 
 		const auto res = dlg.ShowModal();
@@ -581,8 +583,6 @@ bool PresetUpdater::config_update() const
 		} else {
 			BOOST_LOG_TRIVIAL(info) << "User refused the update";
 		}
-
-		p->had_config_update = true;
 	} else {
 		BOOST_LOG_TRIVIAL(info) << "No configuration updates available.";
 	}
diff --git a/xs/xsp/GCode.xsp b/xs/xsp/GCode.xsp
index 36b43271c..c1856ccf7 100644
--- a/xs/xsp/GCode.xsp
+++ b/xs/xsp/GCode.xsp
@@ -31,7 +31,7 @@
             try {
                 THIS->do_export(print, path, preview_data);
             } catch (std::exception& e) {
-                croak(e.what());
+                croak("%s\n", e.what());
             }
         %};
 
diff --git a/xs/xsp/GUI_3DScene.xsp b/xs/xsp/GUI_3DScene.xsp
index 8ee88543d..48bd30cd1 100644
--- a/xs/xsp/GUI_3DScene.xsp
+++ b/xs/xsp/GUI_3DScene.xsp
@@ -190,18 +190,6 @@ remove_all_canvases()
     CODE:
         _3DScene::remove_all_canvases();
 
-void
-reset_current_canvas()
-    CODE:
-        _3DScene::reset_current_canvas();
-
-void
-set_active(canvas, active)
-        SV   *canvas;
-        bool active;
-    CODE:
-        _3DScene::set_active((wxGLCanvas*)wxPli_sv_2_object(aTHX_ canvas, "Wx::GLCanvas"), active);
-
 void
 set_as_dirty(canvas)
         SV *canvas;