You can certainly have a script which filters out the JOIN PART QUIT MODE messages from the channel and, if the channel has logging on, writes them to the channel log.
But AFAIK, there is no way for a script to delete a line from a channel window.
doesn't work.
/dline is only for custom windows. So I guess this feature request is to extend dline functionality to allow it to work on channel and query and DCC chat windows.
