I asked about this and got this reply I haven't tried it yet tho.
Hello Justin,
Firstly, chat focus. I regret that there's no feature in our software that
will prevent this (technically it's called "grabbing keyboard focus") -
that is simply the way the software behaves.
If you are using Windows XP, installing the XP Power Toys "TweakUI" module
may work for you. This package, from Microsoft, has a feature
under "General" and "Focus" that prevents applications from stealing the
focus. You can download it from:
http://www.microsoft.com/windowsxp/p.../powertoys.asp
It's free, and I think this will make the software behave in the manner in
which you'd like it to work.
Best regards,
Andrew
PokerStars Support Team