I don't really know the answer to the question but felt bad seeing over 1,000 views and not a single reply. My guess is that it's a browser/os/monitor thing and can't be controlled by code.
I believe what you are seeing there is Quartz in action. WinXP uses a little different method, however they will be adopting something very similar to Quartz in Longhorn... Which they can get started on once they finally figure out SP2