Weird problem here. Do you know what would cause this?
I have a NestedLayoutPanel in the east region of a BorderLayout, which has a center and south region to it. When it's expanded and showing the NestedLayoutPanel, it's alright and doesn't overlap the main BorderLayout's south region, but when I collapse the east region, it resizes the region to the bottom of the viewport, and then the region seems to be z-indexed behind the south region.
Here's a picture of it when it's expanded and it looks correct:
I'm going to try messing with z-index, but I just thought you should know about this odd resizing behavior.