Will you add the possibility to use /silt on the frame box and an option to make the "paint sign"-text go away when we try enter the box. That would be awsome :)
Fantastic mod, good work :)

All signartist commands already work with frame box. Be sure you're running version 1.2.0 or higher to support using commands on photo frames. For normal players locking the box will make it go away and it will say open box instead. For players with the admin or developer flag unfortunately there is no way to hide that as anyone with the flag can by default edit the sign. It's a limit with the client and I haven't found any way around it.