I'm not sure I understand your solution. You mean that the event will fire once a postback occurs, but that you have to insert a seperate submit field to invoke the postback?
Yes, the bug condition and the workaround I said applies to .NET v1.1 web applications, in quite consistant manner.
I have not verified if this trick is needed in v2.0 or above, so you should try to deduce it yourself.
Just create a new webform with just a dropdownlist in a form tag, and put the server side event for onchange there to see if it works.