Since our controls adopt the notion of "skin" all default color properties values (BackColor, ForeColor etc.) are ignored.
You can style the PanelBar in not too complex way, though. Here is an article on creating a custom skin for RadPanelBar: http://www.telerik.com/help/aspnet-ajax/panel_appearancecreatingacustomskin.html
You can check the other articles in the section Appearance and Styling, too.
I hope this will be helpful for you!
the Telerik team
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