You have to remember the name of the thread you want to ignore. Why would you want to do that? :)
OTOH, click Filter once and the thread becomes invisible to you.

>Okay, this is probably a stupid question, but since the threads are named and you have to actually go to the thread to read it, why would one want to "filter" a thread ? I must have a different UT interface or something but I find it incredibly not difficult to not read things I have no interest in <s>