Fun implications of designing [your software update service][msupdate] as a pseudo-application that is actually an ActiveX plugin (that needs to guarantee the owning web page cannot be closed) include refusing to allow _any_ web page to come forward when the owning web page is one of many tabs in Internet Explorer 8.
It is a little satisfying seeing Microsoft’s chickens come home to roost, but I would much rather they hadn’t made such obvious, Web-hostile choices in the first place.
[msupdate]: http://update.microsoft.com/microsoftupdate/v6/default.aspx