Trying to work around 3D scene focus after de-activation of the main

window without having to resort to CallAfter(), which breaks
on Linux with some window managers that follow mouser cursor.
May fix #5620 #6870 #6992

src/slic3r/GUI/MainFrame.cpp

@@ -2101,6 +2101,21 @@ void MainFrame::technology_changed()
 
 }
 
+#if defined(__linux__) || defined(_WIN32)
+// wxWidgets callback to enable / disable window and all its children windows.
+// called by wxWindowDisabler when entering / leaving modal dialog loop.
+// Unfortunately the wxWindowDisabler calls Enable(true) after the wxEVT_ACTIVATE event is processed
+// while MainFrame is not yet enabled, thus restoring focus in OnActivate() handler fails
+// and we need to do it now.
+bool MainFrame::Enable(bool enable)
+{
+    bool retval = DPIFrame::Enable(enable);
+    if (enable && retval)
+        this->plater()->restore_keyboard_focus();
+    return retval;
+}
+#endif
+
 //
 // Called after the Preferences dialog is closed and the program settings are saved.
 // Update the UI based on the current preferences.

src/slic3r/GUI/MainFrame.hpp

@@ -148,6 +148,15 @@ public:
 
     void        update_title();
 
+#if defined(__linux__) || defined(_WIN32)
+    // wxWidgets callback to enable / disable window and all its children windows.
+	// called by wxWindowDisabler when entering / leaving modal dialog loop.
+	// Unfortunately the wxWindowDisabler calls Enable(true) after the wxEVT_ACTIVATE event is processed
+	// while MainFrame is not yet enabled, thus restoring focus in OnActivate() handler fails
+ 	// and we need to do it now.
+    bool        Enable(bool enable = true) override;
+#endif
+
     void        init_tabpanel();
     void        create_preset_tabs();
     void        add_created_tab(Tab* panel, const std::string& bmp_name = "");

src/slic3r/GUI/Plater.cpp

@@ -6303,16 +6303,34 @@ void Plater::force_print_bed_update()
 void Plater::on_activate()
 {
 #if defined(__linux__) || defined(_WIN32)
+    this->restore_keyboard_focus();
+#endif
+	this->p->show_delayed_error_message();
+}
+
+#if defined(__linux__) || defined(_WIN32)
+// wxWidgets callback to enable / disable window and all its children windows.
+// called by wxProgressDialog when entering / leaving modal dialog loop.
+// Unfortunately the wxProgressDialog calls Enable(true) after the wxEVT_ACTIVATE event is processed
+// while MainFrame is not yet enabled, thus restoring focus in OnActivate() handler fails
+// and we need to do it now.
+bool Plater::Enable(bool enable)
+{
+    bool retval = wxPanel::Enable(enable);
+    if (enable && retval)
+        this->restore_keyboard_focus();
+    return retval;
+}
+void Plater::restore_keyboard_focus()
+{
     // Activating the main frame, and no window has keyboard focus.
     // Set the keyboard focus to the visible Canvas3D.
     if (this->p->view3D->IsShown() && wxWindow::FindFocus() != this->p->view3D->get_wxglcanvas())
-        CallAfter([this]() { this->p->view3D->get_wxglcanvas()->SetFocus(); });
+        this->p->view3D->get_wxglcanvas()->SetFocus();
     else if (this->p->preview->IsShown() && wxWindow::FindFocus() != this->p->view3D->get_wxglcanvas())
-        CallAfter([this]() { this->p->preview->get_wxglcanvas()->SetFocus(); });
+        this->p->preview->get_wxglcanvas()->SetFocus();
-#endif
-
-	this->p->show_delayed_error_message();
 }
+#endif // Linux or Windows
 
 // Get vector of extruder colors considering filament color, if extruder color is undefined.
 std::vector<std::string> Plater::get_extruder_colors_from_plater_config(const GCodeProcessorResult* const result) const
@@ -6875,7 +6893,6 @@ wxMenu* Plater::instance_menu()         { return p->menus.instance_menu();
 wxMenu* Plater::layer_menu()            { return p->menus.layer_menu();             }
 wxMenu* Plater::multi_selection_menu()  { return p->menus.multi_selection_menu();   }
 
-
 SuppressBackgroundProcessingUpdate::SuppressBackgroundProcessingUpdate() :
     m_was_scheduled(wxGetApp().plater()->is_background_process_update_scheduled())
 {

src/slic3r/GUI/Plater.hpp

@@ -149,6 +149,16 @@ public:
     void render_project_state_debug_window() const;
 #endif // ENABLE_PROJECT_DIRTY_STATE_DEBUG_WINDOW
 
+#if defined(__linux__) || defined(_WIN32)
+	// wxWidgets callback to enable / disable window and all its children windows.
+	// called by wxProgressDialog when entering / leaving modal dialog loop.
+	// Unfortunately the wxProgressDialog calls Enable(true) after the wxEVT_ACTIVATE event is processed
+	// while MainFrame is not yet enabled, thus restoring focus in OnActivate() handler fails
+	// and we need to do it now.
+    bool Enable(bool enable) override;
+    void restore_keyboard_focus();
+#endif
+
     Sidebar& sidebar();
     const Model& model() const;
     Model& model();