I'm attached a test case. It creates a Frame (undecorated, but this doesn't appear to be necessary) that allows you to resize from the bottom portion of the frame. The frame also contains a Component that will be the size of the Frame instead by 10. If you click in the south portion to resize you'll notice that often times when you release the mouse a repaint isn't triggered, even though the code expclitily invokes validate then repaint. Clicking on the Component will cause its current size to be output, and indicates that the validate was succesful, just that the repaint failed.
I could only get this to happen on Solaris, although it may be reproducable on a slower Windows machine, not sure.