Haven't come across any info along those lines, despite a little bit of prodding
Stances are now being supressed whilst mounted - not sure if this was intended for standard mounts, as they have inherited quite a few features from Warsteeds this round, including physics / inertia. Was done as a result of general outcry in prior rounds when mounting a warsteed would completly cancel all stances, and if you got dismounted during battle were left feeling like a lame duck until you either remounted or got stances back on.
In addition to the the existing skin problems from prior rounds (mainly the mounted combat bank of the toolbar using it's own skin/artwork regardless of what skin you have set - turning it into the usual garbled mess you get on first loading a custom skin) they seem to have introduced another issue this round where if your skinned toolbar is scaled to 1.0 then the quickslots on the main toolbar can't be used until you resize the toolbar bigger / smaller.
Hopefully we can get the tags for those new toolbar buttons sooner rather than later too, I know at the resolution I'm using (1980*1020) the up / down arrows aren't exactly easy to click in a hurry, and their positioning has the up arrow sitting squarely on top of a quickslot