disabling cursor autofocus

I recently noticed that I somehow have cursor autofocus, where whatever the cursor is over attains focus. For example, I'll try to make a new away message, and when I move the cursor out of the way and off the window, the "new away message" window loses focus so I can't type into it, instead typing into whatever window is below it. I'll end up doing an inline search in Firefox o something because the browser window is directly below the current one.
It's really annoying and I'd like to get rid of it (so I have to click to gain focus), but I have no idea how it happened in the first place.

Any ideas?

 

Try this one. With the Registry Editor browse to the key HKEY_CURRENT_USER/Control panel/Mouse. Right click on "focus" and choose "modify". Set the value "Off". Hope it works

 

I don't have a "Focus" entry there. I also looked in HKEY_USERS with no luck. It wouldn't have anything to do with my mouse software (MX518), would it, since there are no such settings. I'm also using XP Pro.
Thanks!

 

Aha! I think TweakUI automatically turns on X-Mouse, which is the autofocus thing. I unchecked it and now everything's fine.