Build : Java2D:29-Sep-98@-3:20
applet : Blink
machine : Orange hw:sun4u OS:2.5.1
desktop : "see content while dragging"

It happens more frequently if the applet has been running for a while. Basically what happens is when you grab the title bar and start dragging the window. The window will stop dragging within few moments all the while the mouse button is down and never released.
It seems to happen more frequently if the applet has been running for 5-10 mins.

I was unable to reproduce on a 5.6 8bit or 24bit screen depth.