>Thats OK when the mouse moves to the control, but how can i trap when the mouse leaves the control ?

You'd have to have surrounding objects MouseMove() events coded to cancel the highlight.
In the FFC there's a class called _mouseoverfx in the _ui.vcx class library. (there's a sample as well - look up "mouseover" in the help file and go to the MouseOver effects topic for more)
It may not do exactly what you want out of the box, but it can be subclassed or otherwise altered. At least it can give you more pointers than I can :)