How can a client identify the window manager version?

[Mart Raudsepp]

Markus Kuhn wrote:
> Is there a standardized way, by which an X11 client application can
> identify the product name and version of the window manager with with it
> interacts? Something like like "fvwm 2.5.10", i.e. the kind of string that the
> window manager would return if called with the command line option --version.
> 
> This would be very useful for:
> 
>   - generation of automatic bug reports by the clients (in case the
>     window manager version is affecting the reproducability of the failure)
> 
>   - adapting client behaviour to particular window managers (e.g., differently
>     phrased help messages or graphical instructions)
> 
> If there is no mechanism for a client to identify the window manager
> name and version, may I suggest such a feature for inclusion in a future
> ICCCM or wm-spec extension?
> 

EWMH says that an EWMH conforming window manager must set the 
_NET_SUPPORTING_WM_CHECK to be a child window creating by itself, whose 
_NET_WM_NAME property is set to the name of the Window Manager:

http://standards.freedesktop.org/wm-spec/wm-spec-1.3.html#id2506451

I have not queried this for myself, but you should be able to get the 
child Window in question from _NET_SUPPORTING_WM_CHECK (with the proper 
handling of cases where it isn't set), and query that child windows 
_NET_WM_NAME then. Personally I am not sure if wm's set the version 
number into there too.


Regards,
Mart Raudsepp