Fix of dark mode detection on macOS 10.12 and 10.13

src/slic3r/GUI/GUI_App.cpp

@@ -332,7 +332,11 @@ unsigned GUI_App::get_colour_approx_luma(const wxColour &colour)
 bool GUI_App::dark_mode()
 {
 #if __APPLE__
-    return mac_dark_mode();
+    // The check for dark mode returns false positive on 10.12 and 10.13,
+    // which allowed setting dark menu bar and dock area, which is
+    // is detected as dark mode. We must run on at least 10.14 where the
+    // proper dark mode was first introduced.
+    return wxPlatformInfo::Get().CheckOSVersion(10, 14) && mac_dark_mode();
 #else
     const unsigned luma = get_colour_approx_luma(wxSystemSettings::GetColour(wxSYS_COLOUR_WINDOW));
     return luma < 128;