| I'm not quite sure what you mean by scrolling a canvas, or how that happens, but if you can figure out that part, here's how you would make it work with the scroll bar.|
You would have to tie a scroll event with your scroll canvas update. In your Event loop, check for event $401 (GadgetAction). When that is detected, if the EventSource is your slider gadget, then that means it has been "scrolled". Check the SliderValue to get the new value of the slider, and then call your "canvas scroll" function with that parameter.
Does that help at all?