Update : Basically, I'm somewhat miffed that, having got an evening free to work on my Facebook app. it keeps giving me this message :
Errors while loading page from application
The URL http://myappurl did not respond.
There are still a few kinks Facebook and the makers of My App
are trying to iron out. We appreciate your patience as we try to fix
these issues. Your problem has been logged - if it persists, please
come back in a few days. Thanks!
That's not true. The URL in question, on my server, responds perfectly well. It's Facebook which is running slow and (probably) timing-out.