Reset g_lastMouseEvent after processing the mouse button release event

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@44342 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/window.cpp

@@ -1682,7 +1682,11 @@ gtk_window_button_release_callback( GtkWidget *widget,
     event.SetEventObject( win );
     event.SetId( win->GetId() );
 
-    return win->GTKProcessEvent(event);
+    bool ret = win->GTKProcessEvent(event);
+    
+    g_lastMouseEvent = NULL;
+    
+    return ret;
 }
 
 //-----------------------------------------------------------------------------