Recently David Della Rocca asked me for adding a way to overwrite the draw methods of a NSScroller in Real Studio. Well, we had already a NSScrollerMBS class, but as with all classes, simply overwriting the methods in Real Studio doesn't overwrite them for Cocoa. So I had to create a new class: CustomNSScrollerMBS.
This class allows you to overwrite drawing and other things, so you can customize it. With a little work David created a nice example project which we'll include in our examples in the future.
It's also a nice example on how to use NSScrollViewMBS to make a view which can be scrolled with gestures and also supports bouncing on the edges in latest Mac OS X versions.