When I click on a creative tab, and I move the mouse while I'm holding the button and then I loose the button anywhere that isn't a creative tab, cause the tab doesn't be selected.
But if I do the inverse, I click anywhere that isn't a creative tab and then I move the mouse over any tab, holding the button obviously, and then I loose the button, over the tab, this tab is selected.

I think it should work like Options Menu, it works when you click on a option button not when you loose it.

I hope you understand me