Trigger action on fully scrolling a WebObject

Hi there,

maybe one of you JavaScript gurus out there can help me out here...

I have a slide with a WebObject (another Captivate project slide, actually), which displays with a horizontal scrollbar, as it exceeds the dimensions of the hosting project in width. I'd like an action to be triggered (show a custom next button), when the learner scrolls the WebObject all the way to the right (or so many pixels to the right, if that's easier). Is there any way to detect the scrollbar status via js and fire actions based on it?