Hello Benjamin, 

I also agree that this behavior needs to be fixed in our RadTreeView control. I have already forwarded this issue to our development team for further investigation. You can follow the feedback item here to receive updates on its status. This way, you'll stay informed about its current progress.

Regards,
Dinko | Tech Support Engineer
Progress Telerik

Hi Benjamin,

Thank you for pointing out that the workaround does not work when removing a node. I have checked this and I think I found a better solution which handles both scenarios. You can update the scroll range by calling the UpdateScrollRange() method. You can call the method in the NodeExpandedChanged event. So far, I could not find a better place than in this event handler.

private void RadTreeView1_NodeExpandedChanged(object sender, RadTreeViewEventArgs e)
{
    this.radTreeView1.TreeViewElement.Scroller.UpdateScrollRange();
}

Give this approach a try and share if it works for you.

Regards,
Dinko | Tech Support Engineer
Progress Telerik

Hello Benjamin,

Thank you for reporting this behavior. As a workaround, we can ignore collapsing the children in the node from which we call the Collapse() method. This can be done by passing true as a parameter to the method. The default value is false.

this.radTreeView1.Nodes[0].Collapse(true);

Regards,
Dinko | Tech Support Engineer
Progress Telerik