bug#28945: 25.2; desktop auto save timer does not work

[Eli Zaretskii <eliz@gnu.org>]

> From: Peter Neidhardt <pe.neidhardt@googlemail.com>
> Cc: 28945@debbugs.gnu.org
> Date: Mon, 23 Oct 2017 20:57:17 +0100
> 
> > How many frames and how many buffers do you typically have in a
> > session?
> 
> Only one frame (I use EXWM), but dozens of buffers, typically between 10-50.

Well, I typically have around 5 frames, and several hundreds of
buffers.

> The manual has this:
> 
> > When ‘desktop-save-mode’ is active and the desktop file exists, Emacs
> > auto-saves it every ‘desktop-auto-save-timeout’ seconds, if that is
> > non-‘nil’ and non-zero.
> 
> It's terribly misleading: it does not mention that it only saves when
> idle while "every" is wrong here considering that it saves only once
> until the window configuration gets changed.

Yes, and your report mentioned it.  We'll get to that, my point was
just about the suggestion to make the default timeout shorter, not
about all the rest of your report.