Is it possible to import a window and all its contents from 7.3.3 to 7.2.10?
No, you are able to import from an older version of Ignition to a newer version, but not from newer to older.
I used to be able to get a mostly working backwards compatible one by massaging the file a bit, but now the structures are different enough that even the hack-around won’t work.
Not complaining, though. Now I got a challenge!