-    global _wxPyCallAfterId
-    if _wxPyCallAfterId is None:
-        _wxPyCallAfterId = wx.NewEventType()
-        app.Connect(-1, -1, _wxPyCallAfterId,
-              lambda event: event.callable(*event.args, **event.kw) )
+    if not hasattr(app, "_CallAfterId"):
+        app._CallAfterId = wx.NewEventType()
+        app.Connect(-1, -1, app._CallAfterId,
+                    lambda event: event.callable(*event.args, **event.kw) )