In this case:
I've seen this similar in other games (in game; if you wanted to PM [ie. clan members/single person]) you could type something like:
/m
ie: /m XJC hey what's up?
- and it would send it to all members with XJC in their name with the message "hey what's up?" - seen in games like RtCW: Enemy Territory. That's a workaround from Alt+Tabbing to another chat client.