Re: Weirdness with Emacs' X window id

[Jan D.]

Peter Heslin wrote:

> In Debian GNU/Linux:
>
> If I do emacs -q --no-site-file with a month-old CVS checkout, and
> then M-x eshell:
>
> ~ $ xdpyinfo |grep -i focus
> focus:  window 0x1400015, revert to Parent
> ~ $ wmctrl -l |grep -i emacs
> 0x01400014 1 aideen Emacs *eshell*
>
> where wmctrl is a command-line program and the -l switch makes it list
> all current windows.  Note that xdpyinfo and wmctrl disagree as to
> what should be the ID number for the single Emacs frame.  One says a
> number ending in 14, the other in 15.
>
> wmctrl -l does not know of any window with the ID 0x1400015.
>
> Is this expected?  I don't know anything about these IDs -- I'm just
> trying to write a script to manipulate windows on my desktop, and
> it's quite difficult with this ID schizophrenia.
>
> Emacs is the only application I run that behaves like this.
>
> If it's not expected behavior, then it could be a bug in wmctrl,
> xdpyinfo, my X server, Emacs, or who knows where, so it would be
> interesting to see if anyone else sees this.

It is normal.  The window manager may set windows between the Emacs 
window and the root window.  Also, there is a special window called the 
client leader window used for session handling.  I don't know which 
window wmctrl  returns, it can be any of these.  To see all windows 
Emacs has, use:

% xwininfo -tree -id 0x1400015

(or 14).

   Jan D.