How to overwrite the behavior of split button?

I don't know why you delete my post. But it doesn't matter. I can post it again.

Backgroud

The behavior of split button makes me confused when I use split button collapsing the split panel. It locates in different position when I restore the split button by double-click. What's weirder is that double-click will make no effect when the split button located on the edge. I don't like these default behaviours.

Question

1. Do you know how to overwrite the default behaviour of split button?

2. Is there a virtual method or some event I can reimplement?

3. I want to collapse the right panel to the right side, and restore it to the initial location, and just these to behaviours. How can I do it?

Thanks!