Thank you for contacting me.
Currently, the functionality you want to access is built-in RadTreeView
and you cannot access it via the control's API. However, we will consider improving this in the future releases of RadControls for WinForms.
With the present version you can only modify the Visible
state of the indication forms using the ShowOutlineFeedbackForm
I hope this helps. Please write me back if you have more questions.
the Telerik team