automatically issue `exit' or <cntrl-D> on idle

[Eric Smith <es@xxxxxxxxxxxx>]

As a screen user, I often have at the end of the day a lot of
windows open with just a zsh prompt.  

Instead of having to manually close these, Is is possible to have
zsh automatically issue an `exit' or <cntrl-D> when shell is idle
for more than n seconds.


-- 
- Eric Smith