this is just a suggestion i didn't try,
but maybe you can put another control in the color of the background on the same spot (and size) of the textbox,
thus thatControl_onmouseover = yourTextBox_onmouseover.
maybe a picture box or a label or whatever... i haven't used forms in a long time...
i'm sure there are API's for what you are trying to do, but i think the simple solution is the best.
(not that mine is the simplest solution :))
ok hope it helps,
itay.
