$("div.content-left > *, div.content-main > *" ).live('resize',function(){alert("Size changed")});
does not work, because the resize event only applies to window resizes. But in my case the divs change size late, because the content is loaded late by an ajax request - or by clicking a panel menu. I definatley need to avoid to register on all individual events of the children (ajax, click), because that can be very many different events and then it is not maintainable.