[openbox] Matching OSD windows

[Carlos Pita]

>> I think there is nothing. You could add one around here:
>> https://github.com/danakj/openbox/blob/master/openbox/popup.c#L44
>
> Ok, Dana, I will be posting a patch into the tracker as soon as I can
> take a look at this. Any preferred name for the property/atom? Cheers.

Maybe setting the osd type to _NET_WM_WINDOW_TYPE_MENU will be a
pragmatic approach in the sense that no non standard atom is
introduced and so there is no need to add obscure documentation.
Besides, "menu" is a natural selector for compositors and will work
out of the box. OTOH osds are not exactly menus, one could argue. What
do you think?