It's called an in game message. You should try it. When irc says I am idle then I'm probably idle.
But since you don't know how to in game message The U hear is the easiest way to contact them. Not me. You have no reason to say I'm hiding or ignoring you. It says im idle for a reason. Go pound sand. I am not even playing. If you would have taken a snatch new you would have seen I abandoned. I help the new people and hang out in our channel. You want to diplo or war i said it a million times ralk to erv.