yacsef, if you are talking about the party lock, it is to avoid PM windows to open when you double click a player name on party window, which usually lead to deaths if you play as priest since it activates chat and your hotkeys stop working x.x
chars:
Crazy Bandit - Stalker
Nurelion - Creator (with his amistr Gobball :3) Sarcedos Signat - High Priest
Rulindil - Star Gladiator