I'm 100% converted to Vertical IM tabs. As a performer, I often get huge storms of IMs during and immediately after a show. with the horizontal format, to see who's IM'd me, I need to stretch my IM panel across the whole bloody screen- and even that is not always sufficient. Part of my job is to be friendly with the fans, answer requests, share booking info with potential employers, etc. I REALLY cannot afford to ignore someone just because their IM was buried offscreen. Loving CV for everything else, but I can't convert fully until/unless this becomes an available option. (I'd be happy if someone could hand me a custom XML tweak even.)
EEEEEEEEEEEEK - I so totally disagree! When I perform, half the width of my screen is already eaten up by liner notes, streaming utilities, and other performance tools- and another 25% is eaten by the space where critical blue notes drop, (who has tipped, in particular, and needs to be thanked.) I need my chat window tiny, AND I still need to see who has IMed.
Emerald has had vertical tabs for ages- as does Imprudence. Emerald's users are more than 80% in favor of it, roughly judging by the responses when it was discussed in forums. And Emerald has just hit a very nast snag in the road of it's popularity. There are many users who will be emigrating from it's viewer to others they feel they can more safely trust. I suspect the popularity of the option would be greater than you know. Still- if someone could offer a personally implementable xml patch, that would be plenty good enough for me.