Thank you for your question. Before getting to it, I would like to point you to our License Developer service that the Telerik site offers. If your company has already purchased a license from us, please ask them to add you as the license developer. You can find more information on this here: www.telerik.com/faq/
I've tested the RadPanelBar with the information you have provided. Basically, I added a new instance of RadPanelBar to a ShapedForm, then added three RadPanelBarGroupElements. I've set the EnableHostControlMode
property of the first group to true and added an instance of TreeView into the panel of that group. When I ran the app there was no flickering, so I am not able to reproduce your problem.
It is possible that I am missing something. Could you give me more information on replicating the problem? I will also need information on the style of your RadPanelBar (ListBar, OutLookNavPane, VS2005ToolBox, ExplorerBar), the version of RadControls for WinForms you currently use, and if possible a sample project demonstrating the faulty behavior. You can send us the sample project in a new support ticket.
I'm looking forward to your reply.
the Telerik team