Windowlist menu customization

[Chris Jones]

GNU/screen provides a list of windows in tabular form that you can access via
CTRL+a " or the GNU/screen CTRL+: windowlist command.

By default this list of windows displays rather little information: window
number, window title and flags.

This is basically what users like myself already have at the bottom of the
screen in their "hardstatus line".

I thought it would be nice to display the name of the currently
executing program where relevant and (or) the bash $PWD for those
windows that are currently idle just displaying the shell prompt.

The idea is to use this display to have some kind of overview of what is
currently going on in a given GNU/screen session.

To clarify:

I have (say).. a vim session running in window #3, gdb running in window #4,
and perhaps less /tmp/xxxx.log on windows #5, a man page on windows #6, and
somewhat unrelated... some kind of audio player running in window #10.

As to windows #7 to #9 as well as #11 and #12 they are currently displaying the
bash prompt and are basically available to do whatever I fancy at this point.

Regarding windows #0, #1, and #2 they run e.g. a python interactive shell, the
mutt mailer agent, and the text-mode Elinks web browser... 

Lines such as this in my .screenrc:

  screen -t P $SHELL -c "python"
  screen -t P $SHELL -c "mutt -y"

start these "static" windows when I launch the GNU/screen session. 

I know where they are and their content never changes during the life of
the screen session.

The default setting for the windowlist string that formats the entries is like
so:

  windowlist string "%3n %t%=%f"

causing the windowlist screen to display for each entry, the window number (%n)
the window title (%t) and the right-aligned window flags (%=%f)

I looked into adding the last executed command - adding the %x STRING ESCAPE 
eg. 

  windowlist string "%3n %t %x%=%f"

but alas '%x' remains set to the value of the initial command - ie. the
command that is issued at session startup, (or the default shell when
the window is created on the fly via eg. CTRL+a c). 

And that is usually just '/bin/bash'... with optionally whatever command
was specified via the screen command - e.g.something like screen -t
M $SHELL -c "mutt -y" will cause the windowlist (aka CTRL_A ") to
display '/bin/bash -c mutt -y'. 

After that the value of the %x STRING ESCAPE is not updated to keep
track of what is actually happening in each window in terms of what is
currently running on top of the bash shell.

I also looked into using a backtick that returns what I am looking for via
something like:

  windowlist string "%3n %t %8`%=%f"

where '%8`' would have been defined to screen like so:

  backtick 8 0 0 /home/cjones/bin/bt-wlist

... but I haven't been able to find anything (such as an environment variable)
that would let the code in the backtick script figure out anything about what
is happening in each GNU/screen window.

As far as I can tell, nothing useful in terms of windows content (param or
environment variable) is passed by GNU/screen to the backtick script when it
is given control.

Hitting a wall at this point and wondering whether anyone more knowledgeable
has gone down this path before and mignt have any suggestions.

Thanks,

CJ
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