> Not wanting to start a debate on this again, please do not blame

the service

> pack for correcting things, blame your application for being

reliant on

> errorious behavier. Good software is programmed to use documented

and

> supported apis. Undocumented features of the windows api tend to

change and

> applications using these are known to break on updates. Good

software does

> not.

I'm not agree.
For example a CreateRectRgnIndirect function works differently with
the same set of input rectangles in NT4 and in 2000. But nowhere in
the MSDN docs written that input rectangles must be specifically
ordered.
So in service pack MS may change some internal things which as the
result will change a docummented function's behaviour.