I have VS2008 and ASP.NET 3.5.  I began converting an application to use the new ComboBox.  In the process, I've come across two bits of design-time behavior that needs pointed out.

First, I write using "Code Behind".

After placing a ComboBox on a page and setting AutoPostBack to True, the "onSelectedIndexChanged" attribute does NOT automatically get appended to the markup when I either double-click on the ComboBox in design view or when I select "ComboBox1 - SelectedIndexChanged" in the drop-downs when viewing the code.  The procedure is created in code but I run into a script error because the event was not added to the control.

Second, when NOT using Code Behind, I click on the drop-down to select the ComboBox control and several of the events DO NOT appear that appear in the cooresponding drop-down that appear when using Code Behind.

Minor problem but irritating to have to manually add the "onSelectedIndexChanged" to the ComboBox control to avoid the script error.

CC

Actually, it has proven worse for my particular project.  Even MANUALLY adding the event handler to the control still results in s script error.

I have reverted the project BACK to DropDownLists...  I need to get work done, not fiddle with obscure problems. 

I took one more look at this control in a much smaller project.  Much smaller.  Only controls on a page were one combo box, a gridview and a couple of labels, a checkbox and a button.  It seems there is some script generated by the combo box control.  I tested the page and all worked fine.   However, then I selected a new item in the combo box, I would get a script error unrelated to any code I had written.  All controls were in an updated panel.  I changed to combo box to a dropdown control and the problem went away.  I don't think this control is quite ready.