Ditto - thank you Chris (and James & others) for the update and comments.
I realize (now) I painted myself in to a corner with the vertical test branch: I misunderstood the status of the various test branches and hard-mounted my monitor in an enclosure. Switching back to 2.8 and stable PB would be a very painful step back unless I temporarily mounted a second monitor horizontally.
Sorry I'm not competent to do any development work, but I'm happy to do any testing and bug reporting.
