bug#25851: 25.2; GTK warning when starting Emacs when desktop file has more than one frame

[martin rudalics]

> ISTR that there was a long discussion about this when Juanma
> implemented these features, so the current behavior is not just a
> random choice on his part.
>
> FWIW, I'm rather fond of the current behavior, since whenever I need
> to restart Emacs, it recreates the precise frame arrangement I had
> when I shut it down.

According to a comment in gtkwindow.c:

 * If you are saving and restoring your application's window
 * positions, you should know that it's impossible for applications to
 * do this without getting it somewhat wrong because applications do
 * not have sufficient knowledge of window manager state. The Correct
 * Mechanism is to support the session management protocol (see the
 * "GnomeClient" object in the GNOME libraries for example) and allow
 * the window manager to save your window sizes and positions.

Just to explain where my doubts come from.

martin