Also use F4 as short-cut for opening pop-up

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@56072 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/combog.cpp

@@ -430,7 +430,8 @@ bool wxGenericComboCtrl::IsKeyPopupToggle(const wxKeyEvent& event) const
     }
     else
     {
-        if ( keycode == WXK_DOWN && event.AltDown() )
+        if ( (keycode == WXK_DOWN && event.AltDown()) ||
+             (keycode == WXK_F4) )
             return true;
     }