Unfortunately, I've already invited usability testers for next week. The usability tests run from Monday through Thursday. I don't think it's likely I'll get a fix for this by Monday.
So what I think I'll do is this:
- I'll boot the test laptop into GNOME 3.12, using the bootable USB flash drive (the one from the Getting GNOME page)
- Tester does the scenario tasks for gedit, on GNOME 3.12
- I'll reboot the laptop into Fedora 20 & GNOME 3.10
- Tester does the scenario tasks for Web, Software, Nautilus, and Notes
It's not ideal, but the big UI changes in GNOME between 3.10 and 3.12 (for my scenarios) seem to be in gedit, anyway. The other programs seem to have the same interface, the same behavior. Or if there are differences, I didn't notice them right away. This seems to be suggested by GNOME designer Allan Day recommendation to test "gedit (development version only)," from when I was planning my research.