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When you upgraded to the latest version of Sitefinity the RadControls for ASP.NET AJAX has been upgraded too. This means that there might have been changes in the RadPanelBar control which would produce this behavior. I have noticed that you had a support ticket open with the same issue. Could you send us there the skin for the panel bar you are using (master page, theme and skin) and we will try to see the behavior on our side. Probably you could provide us with a live link so that we can observe the behavior there.
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