I had a functioning custom scrollbar in Catalyst CS5.5, and through the course of tweeking my design, the scrollbar has refused to work anymore. No matter how many times I redefine the datalist/scrollbar, it refuses to work. I've tried restarting Catalyst, all to no avail.
The datalist may or may not accept mouse clicks, if it does I can arrow through the list, but I cannot drag the thumb. Sometimes neither the thumb or the arrow keys will work on the datalist.
Why the squirrley behavior?
I got my scrollbar to work, before I attached it to the datalist. Once I attached it to the datalist, it was frozen again. There was plenty of data in the list. I could arrow through it and the thumb would move, but it would not let me drag with the mouse.
Through SHEER LUCK, I ran across Brian Woods' video on creating a datalist, and in passing he mentioned resizing the Repeating Items bounding box to make sure it doesn't overlap the scrollbar. Failing to do that will make the scrollbar unuseable.
Thanks Brian Woods!