Disabling just part of a button

Hey everyone!

Had a quick question.
Is there a way to disable just part of a button?

I hav a button that when mouseovered it goes up 10 pixels and when mouseout it goes back down 10 px. Yet if I put my mouse in the wrong spot, i will go up and down really quick and start jittering.

So what I need to do is have a certain area that is inactive in the button. Either by putting somthing in a layer above it. I don’t know…

Any ideas?

Thanks!