I recently installed the November release of the AjaxToolkit, and just discovered this bug (in production no less). It seems that OnActiveTabChanged is firing even when it ISN'T changing. It fires on every postback.
Comments: I have exactly the same problem, and the impact is not low, it's quite important. Imagine a repeater, with a button performing on postback some action based on some selection boxes on the repeater. When we click the button, the TabChanged event fires BEFORE the button click, and in its handler we might have code to reload the data. The repeater is reloaded, and the selection boxes are reset. The click event actually fires and the code selects the wrong elements...
Comments: I have exactly the same problem, and the impact is not low, it's quite important. Imagine a repeater, with a button performing on postback some action based on some selection boxes on the repeater. When we click the button, the TabChanged event fires BEFORE the button click, and in its handler we might have code to reload the data. The repeater is reloaded, and the selection boxes are reset. The click event actually fires and the code selects the wrong elements...