My only additional comment here without re-hashing what I have already posted.
I don't think there is any way to expect a thread, no matter what forum it is in, to stay on topic. Threads drift... it is just what happens.
Then, more on filtering:
As far as filtering OUT a pre-fix... I wouldn't be surprised if there were a way to do it. But, I don't know how. I just tried it and don't see a way. The URL when you filter has something like prefix= in it. I tried to put a blank space in it thinking that would give posts without a pre-fix, but it didn't work.
BOb
|