Can the tabs widget respond to a tab being clicked?

Can the tabs widget respond to a tab being clicked?

I want to respond to each tab in my tab widget being clicked, so that I can do a "just in time" population of html in the tab's content area. According to  http://api.jqueryui.com/tabs/, I'm not seeing whether there is such an event. There must be...where? which one? How to do it?