I have some TabItems in the xamTabControl, whose contents should be displayed under some circumstances. Otherwise, the user gets a message box and goes back to the previously selected TabItem.

I tried handling the PreviewMouseDown and PreviewMouseLeftButtonDown on the TabItemEx  and xamTabControl. I can check for the condition, but the user still gets to view the contents of the TabItem even if the condition is false. Handling the routed event (setting e.Handled=true) does not get the desired result.

Does anyone know why?