kivy/kivy — pull request #564 by akshayaurora (2012-07-09 11:30:38+00:00)
Title: UIX: Widget: ensure widget is removed from any parent before adding it.

should fix: #562

Took the approach of adding this in Widget itself instead just in popup as,
I've seen many situations when a Widget is accidentally made a child of
more than one Widgets and in all of them the result is a Clock->max iteration error.