Ever get disconnected and lose a long post? That should happen a whole lot less. Xenforo automatically saves drafts of posts every 30-60 seconds, so if you disconnect, or reconnect later from another device, the draft will be there and can be resumed.
This is the result of typing the above, waiting 60 seconds, closing the window and reopening it again and going back to the thread. The draft appears in grey, and can simply be resumed from here.
I believe (but have not tested) that drafts disappear after 24 hours, so don’t wait forever.
This functionality can also be triggered deliberately by clicking the draft button (the one that looks like a 3.5″ floppy, for those of us who remember those:)