You can access any control embedded in a RadPanelBar's template.
The FindControl method provides you with a reference to any control
inside any of the templates used in the RadPanelBar or any of its PanelItems. You
have to make sure that you properly typecast the returned value as FindControl
returns a reference to a Control class.
After you get the reference you may modify any properties of the referenced control.
In this example the Text properties of the three TextBoxes are