Tab characters work in Custom @Windows for columnization. You can even define Tab Stops to dictate each column's edge. Up until the latest version (or 2) of mIRC, tabs were not respected in channel / query windows, an very few IRC clients actually do tab character expansion. Not sure why Khaled decided this is something mIRC needs now, but you shouldn't use it because you can't guarantee everyone will see what you see, the way you see it.
If you must use fixed column spacing in something you print to a channel / query window, then send sequences of $chr(160) non-breaking [hard] spaces.
