@Azruulei Aye, I think two things would be good, one to actually use the full width of the screen, the right bar doesn't need to be the same size so shrink it, move it out, then split the width amongst the two remaining.
Once all that is done I'd say allow column collapsing, preferrably allowing you to just hide a column or let other columns take over the width to use it too. Even better if you can dynamically fade old messages or inactive columns.
