bug#62164: 29.0.60; ediff behaves poorly by default on tiling window managers

[Po Lu via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Spencer Baugh <sbaugh@janestreet.com> writes:

> I don't know how to name the variable to incorporate both you and Po's
> feedback.  The name of the variable can either include "utility" to
> describe its implementation, or include "floating" to describe its
> effect on most window managers.  (Or include neither, and describe
> nothing, which seems worse.)
>
> I personally prefer your variable name, since I still don't know of any
> window managers that don't float utility windows, but I don't care much.

Dtwm.  Or any window manager that doesn't really support the EWMH, for
that matter.  I would simply suggest:

(defun ediff-make-control-frame-utility-window nil
  "If non-nil, make the Ediff control frame a ``utility window''.

Most X window managers will then order the control frame above all other
windows as long as it remains visible.")

I strongly object to Emacs trying to document behavior that is actually
defined by individual window managers, because we will receive
complaints from users about Emacs not behaving as expected, when in fact
it is their window manager that behaves differently.