We're trying to use a RadTabStrip for navigation, where root tabs are categories, and their sub-tabs are locations. To handle the navigation, I've set up a OnTabClick server-side event, which works fine, except that it doesn't discriminate between the category (root) tabs and the location (sub) tabs, so I got a post-back for both, which was undesirable. To try and compensate for this, I set up a client-side event handler, OnClientTabSelecting, where I call "eventArgs.set_cancel(true);" if the selected tab is a root tab. This prevents the post-back, but it also stops them from being selected altogether, so now I'm stuck on the first category tab, because clicking any of the others results in nothing happening.

Do you have any suggestions for how to solve my problem? That is, client-side tab selection for root tabs, and server-side tab click event for sub tabs.

I can't believe I didn't see that property. Thank you for your swift and helpful answer. :-)