GUI vs TTY when saving & restoring framesets

[Juanma Barranquero <lekktu@gmail.com>]

I've seen that there were several bugs related to framesets and ttys
(I've located bug#17693 and bug#24298, but there were perhaps others).

I don't understand yet the problems and the way they were fixed, but
it has changed one previous feature.

You could do

(1)  emacs -f desktop-save-mode -f destop-read

set up your frame configuration with a couple of frames, save the desktop, then

(2)  emacs -f desktop-save-mode -f desktop-read -nw

and you would get the same number of frames, then again

(3)  emacs -f desktop-save-mode -f desktop-read -nw

and you would get back the original graphics frames.

As of the current trunk, assuming you had 2 frames in (1), when you do
(2) you gent a message

  Desktop: 2 frames, 0 buffers restored.

which I think is false, because "C-x 5 o" does not switch to F2. Then,
if you exit emacs, (3) produces a warning  "Error (frameset): Font
'tty' is not defined.

So, basically, previously the frameset saving in desktop.el was
intended to be unaffected by -nw (per se; of course changes to the
frames would be reflected in subsequent configurations, but not just
entering and exiting -nw), and now it's not.

I sort of liked the previous behavior, which was (bugs aside) safer.
But if the new behavior is preferred, I think there's quite a lot of
code from frameset.el that deals with the gui -> tty -> gui trip and
could be excised.

Opinions?