I'm using a PopUpButton with a custom menu (PopUpMenuButton doesn't quite do what I need), and I find that in some situations, the .popUp property is reset to null. The PopUpButton in question is never taken off the display list, and in the source, that's the only thing I can see that could update this, other than explicitly calling the setter, which I am pretty sure I'm *not* doing. Any ideas? This seems to happen especially when the window is resized.
Thanks, Maciek