Set wxFocusEvent's window value for wxEVT_KILL_FOCUS in wxGTK.

Note that it is still not set for wxEVT_SET_FOCUS, because it's not
immediately obvious how to obtain the previously focused window from
there. It's still better than always having the window NULL.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@69467 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/window.cpp

@@ -3170,6 +3170,7 @@ void wxWindowGTK::GTKHandleFocusOutNoDeferring()
 
     wxFocusEvent event( wxEVT_KILL_FOCUS, GetId() );
     event.SetEventObject( this );
+    event.SetWindow( FindFocus() );
     GTKProcessEvent( event );
 }