Run ditherTest (demo/applets/DietherTest/example1.html). Set the Horizontal
color to be Alpha and click the New Image button. Now drag the window partially
off-screen and then move it quickly around the desktop. You should see
rendering happening in the wrong place - both inside and outside the application
window. When the window stops moving, you'll probably see some of the
artifacts still present, like bars of incorrect color in the image area.

Note that this bug also appears in jdk1.3.