When you try to edit existing event in new manage iCAL events, IE7 will crash and will apear blank withe page. If you try to navigate youre brouser back and then refresh the page, editing event will apear, but when you go to Calendar tab (if you want to change repeat options) you will get this :
[attachment=0:2huc3of6]<!-- ia0 -->jevents1.5alpha.jpg<!-- ia0 -->[/attachment:2huc3of6]
As you can see no other option, then start date is avaible.