Run the code,

Expand sequentually:
1) root
2) data-0-0
3) data-1-0

Scroll to the bottom.
Expand
1) data-0-2
2) data-1-0

try to expand data-1-1
Instead of scrolling, after mouse click on the arrow, I see scrolling to the end.

It is important, as breaks jemmyfx expansion logic, because click doesn't affect.