From the IT side, I can imagine a few possibilities. 1) restore from file-based backup 2) restore entire VM from backup or 3) follow the general instructions to upgrade: https://fmhelp.filemaker.com/docs/13/en/fms13_getting_started.pdf . Basically uninstall 13, clear java cache, put old 12 files back, install 12.
I didn't research much, but I didn't see much about 13 actually doing much to v12 files. So maybe it's possible your v13 edits of FP12 files will still run in v12. Interesting to experiment.
Downgrade from 13 to 12 is possible only if you didn't use too much of the new features that came with FM13 like the pop-overs etc.
If you used pop-overs, every object that you put inside the pop-overs are gone.
Yes, we're talking about FMS. And yes, if you have FMS12 and the clients are FMP13 all features should be available.
What is the point in developing in FMP13 when you know you're IWP clients will not see features native only to WebDirect like pop-overs?
If all my clients are pure FMP with no IWP, then of course I would use FMP13.
At the end of the day, it's personal preference, and with my setup I have to use FMP12 on my FMS12.
Apologize for not being clear at the get go, I should have said both FMP12 and FMS12.