Came up with this, tell me what you think:
I put the check for the separators into a proc called lang::message::check, together with the check performed into lang::message::register to ensure a message contains all the variables required for substitution. This proc should contain all the semantic and sanity checks to be performed on messages now and in the future.
The new proc was then put into 3 places:
- lang::message::register in place of the former check
- a new regression test called lang_messages_correct, which performs the check on every message
- the on_submit block of the message key setting form, displaying an error on the form field when the check fails
If sounds reasonable to you I can send the patches
