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.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 = "");