MSW specific: Fixed update of the UI after system color change.

Note: the wxEVT_SYS_COLOUR_CHANGED event works only for high contrast settings under MSW.

+ ConfigSnapshotDialog: Fixed UI colors for dark mode on all platforms

src/slic3r/GUI/Tab.cpp

@@ -1002,7 +1002,9 @@ void Tab::sys_color_changed()
     for (ScalableBitmap& bmp : m_scaled_icons_list)
         m_icons->Add(bmp.bmp());
     m_treectrl->AssignImageList(m_icons);
-
+#ifdef __WXMSW__
+    m_treectrl->SetBackgroundColour(wxSystemSettings::GetColour(wxSYS_COLOUR_WINDOW));
+#endif
     // Colors for ui "decoration"
     update_label_colours();