Hello Nikolay Velizhanin,
If you want to accomplish the desired functionality then you have to change the ItemPanel of RadTreeViewItem. Please find attached project. Its you can see how to change the panel.
If you have further questions please do not hesitate to ask us.
I hope this will help you.
the Telerik team
Watch a video
on how to optimize your support resource searches and
check out more tips
on the blogs.
Follow the status of features or bugs in
and vote for them to affect their priority.