When using decorated frames under Java Web Start the cursor is not reset when
it enters the "Java Application Window" section of the window. MetalRootPaneUI
has some support for saving and restoring cursors, but not fine grain enough to handle this case. If you have problems resizing the demo, this is already filed
under bug 4777616 which is how I came across this issue.

http://java.sun.com/docs/books/tutorial/uiswing/components/example-1dot4/index.html#ButtonDemo