AJAX TabPanel and HeaderTemplate Visibility
I had a setup where I had an ajax tab panel, with a HeaderTemplate set with a label inside. This label was there as a placeholder using an expression statement (<%$ %>). What I found out though is that I had a label control inside the header template that, for whatever reason, still shows whenever you set TabPanel.Visible = false. So, when setting the tab panel to false, it hides the nice tabbed image background, but keeps showing the label inside the tabs!
So, when changing the visibility of the tab, I also had to change the visibility of the inner header template label. This seems weird, but hey whatever gets it to work is fine with me.