bug#36894: Restore frameset focus and selectedness

[Juri Linkov]

>> Maybe then the desktop should save the selectedness as well.
>
> You mean, restore last-focus-update?  If you add it to
> desktop-globals-to-save, is it restored?

'last-focus-update' is a frame parameter saved in 'desktop-saved-frameset'.

>> > But I asked for a reproducible recipe, and I don't think you have
>> > shown one.  Could you please do that?  I'd like to study it.
>> 
>> In your case above, if you save the frames is such order that
>> the selected frame is not saved last, can you reproduce the problem?
>> I see this problem often when the last frame is not selected.
>
> How can this happen?  In my use, desktop is saved when I kill Emacs,
> and in that case the selected frame is always the last one saved.
>
> That's hwy I asked for a reproducible recipe: I think there are some
> factors at work on your system which I don't understand.

Indeed something strange happens, here is a complete recipe:

0. emacs -Q
1. C-h C-t   (view-emacs-todo)
2. C-x 5 2   (make-frame-command)
3. C-h C-n   (view-emacs-news)
4. C-x 5 o   (other-frame)
5. M-x desktop-save RET RET
6. C-x C-c

7. emacs -Q -f desktop-read --eval '(message "selected-frame: %S" 
(selected-frame))'
8. M-: (selected-frame) RET

9. In the *Messages* buffer the printed selected-frame is not the same.
   See more explanations of messages in the *Messages* buffer below:

The next message comes from 'message' added to frameset.el:
frameset-restore frame-list: (#<frame emacs@localhost 0x5572e78000c0> #<frame 
emacs@localhost 0x5572e71a9eb0>)

The next message comes from 'message' added to frameset.el:
frameset-restore selected-frame: #<frame emacs@localhost 0x5572e71a9eb0>

The next message comes from desktop.el:
Desktop: 2 frames, 2 buffers restored.

The next message comes from 'message' added to desktop.el:
desktop-read selected-frame: #<frame TODO 0x5572e71a9eb0>

The next message comes from 'message' on the command line:
selected-frame: #<frame TODO 0x5572e71a9eb0>

The next message comes from 'message' added to startup.el:
normal-top-level selected-frame: #<frame TODO 0x5572e71a9eb0>

The next message comes from M-: (selected-frame)
#<frame  *Minibuf-1* 0x5572e78000c0>

Here 0x5572e71a9eb0 is the frame with TODO, and 0x5572e78000c0 with NEWS.
(0x5572e71a9eb0 was reused, but 0x5572e78000c0 is a new frame created by 
frameset-restore)
After loading the former should be selected, but actually the latter is 
selected.

The 'message' added at the end of 'normal-top-level' shows one value
of selected-frame, but evaluating M-: (selected-frame) immediately after loading
shows another value of selected-frame.

Conclusion:
The window manager always selects the last created frame, i.e.
it seems it's impossible to create a new frame without selecting it.

Here is complete information:

In GNU Emacs 27.0.50 (build 84, x86_64-pc-linux-gnu, GTK+ Version 3.22.30)
 of 2019-08-13 built on localhost
Repository revision: 2b329ed420eb15f6738edd402697ac2876b2aa61
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.11906000
System Description: Linux Mint 19.1

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