This is just plain untrue.
When in a fullscreen application or a game, even Microsofts own Microsoft Security Essentials will steal focus when auto-updating. Happened to me last night while playing Empire: Total War, and a quick google will reveal fellow sufferers (http://www.technipages.com/prevent-other-windows-from-popping-up-and-stealing-focus.html for
example).
I have a far worse problem however.
MSSE only may do this once a day, but I also use a VPN connection to surf the internet. Whenever that VPN connection breaks down, the same issue occurs. Any fullscreen application is catapulted back to the stupid "connection lost / error message / redial
in x seconds" window and I have not found a single option to get around this.
Since the VPN is quite unstable, I get constantly interrupted.
I understand that it's too late for this to be fixed for XP, where there was an explicit option to suppress the DUN notifications that, of course, did NOT work(you still got catapulted back to the desktop just like in Win7, guess it runs in the family),
but as someone who not only is using a legit Win7, but also a MS Mouse and MS Keyboard, I would expect to at least be able to work or play without being hassled by the OS I am operating under. I've bought all the sacrificial lambs to appease the angry MS OS,
for crying out loud!
After half an hour of googling, all I have found is regkey hacks that (supposedly) don't apply anymore, or only work if the app is already open and minimized or simple venting and frustration.
So much for for Win7 aiming at reducing classic Win annoyances.
Is there any option, setting, reghack, workaround or planned fix that might fix this decade long annoyance of attention-craving DUN-error-messages?