To reproduce:
- Add a RadTreeView which have parent and child nodes to a form.
- Expand nodes until the both scrollbars are simultaneously shown.
- You will notice that you cannot scroll to the last item.

Workaround:
- Subscribe to the following ScrollerUpdated event handler:

void Scroller_ScrollerUpdated(object sender, EventArgs e)
{
radTreeView1.TreeViewElement.InvalidateMeasure();

}

- You can subscribe to this event with the following line of code:
radTreeView1.TreeViewElement.Scroller.ScrollerUpdated += Scroller_ScrollerUpdated;