Clemerson,
It looks like you have a button you want in an up or down state. I believe you can define two bitmaps when you define the button, then use the oBtn:toogle() to change the state of the button, and the bitmap will change automatically. I haven't tried this (or at least I don't remember if I have)
![Wink ;-)](./images/smilies/icon_wink.gif)
.
Check the manual for the syntax for defining two bitmaps.
James