I will be away for a few days on holidy now, back on sunday before I can play, but the problem itself with Mantle is usually intermittent, and I dont know a sure way to provoke it, but if it happens again I will mention it.
I posted a few images of it in the 14.4 thread
. And if you want to see it live, I PM'ed you a link to a .mov file. Not much use, except pretty much the trippiest hang since C64 days.
As for the other thing, Anandtech also mentioned it as no support for portrair-landscape-portrait support, so that is a feature request, not a bug
Really appreciate it though.