I am not sure whether you mean that the RadPane or the RadSlidingPane is not correctly collapsed/expanded when you use its client-side API. That is why I tested both the controls in the following demos:
However, both the demos work as expected under FF2. Would you please prepare a sample reproduction demo, open a new support ticket and send it to me along with detailed reproduction instructions and explanations of the actual and the desired behavior. Once I receive it, I will do my best to help.
the Telerik team
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