FIX: [STUDIO-2186] hide PopupWindow on alt-tab

Change-Id: Ie1bffdd9ace2c6e05979743da9f75ca2c1e87cf3

src/slic3r/GUI/Widgets/DropDown.hpp

@@ -4,6 +4,7 @@
 #include <wx/stattext.h>
 #include "../wxExtensions.hpp"
 #include "StateHandler.hpp"
+#include "PopupWindow.hpp"
 
 #define DD_NO_CHECK_ICON    0x0001
 #define DD_NO_TEXT          0x0002
@@ -11,7 +12,7 @@
 
 wxDECLARE_EVENT(EVT_DISMISS, wxCommandEvent);
 
-class DropDown : public wxPopupTransientWindow
+class DropDown : public PopupWindow
 {
     std::vector<wxString> &       texts;
     std::vector<wxBitmap> &     icons;