http://bugs.winehq.org/show_bug.cgi?id=32394
--- Comment #6 from Mark K markk@clara.co.uk 2012-12-10 13:04:03 CST --- In Windows, as you drag to increase the size of the window newly-revealed areas are filled with grey as with Wine. But as soon as you release the mouse button to finish resizing, WinUAE closes and re-opens the window at its new size with re-laid out controls.
Perhaps some message which should be sent to indicate the window sizing operation is complete, isn't being sent by Wine?