I concede, I forgot /filter had a sort feature. And it's actually rather fast. So, perhaps there isn't a real need for my suggestion after all.
Though, it would make it easier for people to discover and use, since it's right there with the tab stop widths, and very related.
I'm not sure a new switch is really necessary, as the proposed format wouldn't interfere with existing scripts using /window -t. But even so, it could be /window -T then if necessary.
For now, I'll just get along with using /filter -wwczt %n 9 @window @window
Thanks, Ouims!
