Stop the timer when the demo is shutdown

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@25326 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

wxPython/demo/LEDNumberCtrl.py

@@ -35,6 +35,10 @@ class TestPanel(wx.Panel):
         self.clock.SetValue(st)
 
 
+    def ShutdownDemo(self):
+        self.timer.Stop()
+        del self.timer
+
 
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