I've switched from GNU Screen to tmux. They're both similar, except that tmux is still maintained.
GNU Screen has a C-a _
("silence") command. This command makes GNU Screen monitor the current window and alert me when there's been 30 seconds of inactivity. This is quite useful: for example, GNU Screen can watch a long apt-get dist-upgrade
process and alert me when dpkg has a question for me.
Does tmux have an equivalent command? I tried searching the Web but didn't find an answer.