There's a very good reason for Acrobat X not responding with the tool buttons. First, and most important, Acrobat X destroyed the old toolbar concept. In fact, Acrobat X has a completely different UI, and by completely different I don't mean that they rearranged things, I mean they rebuilt the UI from scratch using a completly different technology. So, this new UI pretty much breaks all the old JS UI fucntions. It was Adobe's decission to not update the toolbar functions (includeing the app.hideToolbarButton()) to work with the new Panels and tool butttons. After all, what could you possible want to do with it that they haven't already thought of? Don't worry aobut it. They'll decide what's important for you.