> 
> i was shocked to discover that killing a window (in tmux) does not kill the
> bash procedure running in it.  how would you recommend that a bash function
> check whether it's output is visible anywhere anymore?

I never have used tmux, but for what it is worth you may want to look into
their mailing list or FAQ. See if tmux starts process with "NOHUP" states or
something like that.