def testAddExistingComponent(self):
        c = Label('abc')
        tabSheet = TabSheet()
        tabSheet.addComponent(c)
        tabSheet.addComponent(c)
        itr = tabSheet.getComponentIterator()
        self.assertEquals(c, itr.next())
        self.assertRaises(StopIteration, itr.next)
        self.assertNotEquals(tabSheet.getTab(c), None)