bug#55070: 28.1; desktop-load doesn't work in -nw (non-gui) emacs

[Eli Zaretskii]

> From: Eric Swenson <eric@swenson.org>
> Date: Sat, 23 Apr 2022 07:53:43 -0700
> Cc: 55070@debbugs.gnu.org
> 
> Thanks. It seems really strange that this should be problematic in -nw 
> sessions. I could understand not being able to restore windows between a GUI 
> and -nw sessions, but I don’t see why, since windows work perfectly well in a 
> single frame in a -nw session that restoring them should be problematic.
> 
> Can you explain why this is difficult? In -nw sessions the same commands 
> split windows perfectly well. So clearly -nw sessions support window 
> splitting — why not restoring? (I think a restriction that requires the 
> saving and restoring sessions to be the same kind (either both -nw or both 
> GUI) is a perfectly sensible restriction.

Emacs currently cannot restore windows without also restoring the
frames.  Technically, this is because we use the frameset.el package
as infrastructure for this desktop.el facility.  And restoring frames
in a -nw session will create GUI frames, something the user didn't
intend.  So we disabled that.