ENH:When software is full screen in mac, the sub frame uses the wxSTAYBON_TOP style

jira: STUDIO-11046
Change-Id: Ie1b85e4ac5a5698ec42870349f688924cdf30e21
(cherry picked from commit b28b9c49b208b4269563f59b42ac671fca8035be)

src/slic3r/GUI/BaseTransparentDPIFrame.cpp

@@ -137,6 +137,12 @@ bool BaseTransparentDPIFrame::Show(bool show)
     return DPIFrame::Show(show);
 }
 
+void BaseTransparentDPIFrame::on_full_screen(IntEvent &e) {
+#ifdef __APPLE__
+    SetWindowStyleFlag(GetWindowStyleFlag() | wxSTAY_ON_TOP);
+#endif
+}
+
 void BaseTransparentDPIFrame::on_dpi_changed(const wxRect &suggested_rect)
 {
     m_button_ok->Rescale();