Ah, in which case setting environment variables won't work, because they are only set for the shell you do them in and any children. The launcher isn't a child of your terminal window so nothing changes in its environment. You need to make the launcher change its environment via its config (or some other way, like in a wrapper shell script that does it before launching xed).
Sounds good. Looks as intelligible as uk.d-i-y ever is :-)
Theo (now changed my editor to vim just for fun)