To reproduce:

cd /net/jano.eng/export/disk05/hotspot/sa/classes
/usr/local/java/jdk1.4/solsparc/bin/java sun.jvm.hotspot.HSDB

Select "File" -> "Attach to HotSpot process". Entire window clears to gray
before internal frame asking for PID appears. This did not happen with the 1.3.0
or 1.3.1 2D/Swing. This behavior (flash on create) started in b42.

Click "Cancel" in the resulting dialog; screen flashes again. This behavior
(flash on destroy) is present at least as far back as b39.