def test_multi_tab(self):
d = core.Data(label="hist", x=[[1, 2], [2, 3]])
dc = core.DataCollection([d])
app = GlueApplication(dc)
w1 = app.new_data_viewer(HistogramWidget, data=d)
app.new_tab()
w2 = app.new_data_viewer(HistogramWidget, data=d)
assert app.viewers == ((w1,), (w2,))
self.check_clone(app)
