Flag entire thread?

[peter horst]

I'd like to be able to flag an entire thread with "!": is this possible?
When I tried esc-t'ing a thread, then using ;w, it didn't work--it gave
me the "Set flag? (D/N/O/r/*/!):" message that I expected, but when I
entered "!", nothing happened. Maybe I don't have to do this
to end up with the result I want, which is the ability to limit the
index view to threads I've found interesting. Any help? BTW, it's
1.2.5i.

Peter