expanding scrollbar hides button

I have my ... what do you call it? ... GTK? set up to widen the scroll bar when I hover over it. Problem is that it widens *before* the mouse cursor has moved onto the narrow bar -- it widens as soon as the cursor moves onto the territory that *will be* on the wider bar and thus, if there's a click button at the very edge of the page, it gets hidden by the expanded bar. Would it not make more sense to only expand the bar if the cursor actually moves onto it?