Hello. I think, i've found very annoying bug.
Move your mouse to the column header cell and press the left button, holding it for some time.
Scrolling up must begin, because in MouseSelection controller in OnMouseDown BeginScrollTracking is called and then in the timer handler eventually CustomScrollLineUp is called.
Any thoughts how to fix it?
I think, maybe BeginScrollTracking shouldn't be called if you click on a header cell.