Subject: bug#16028: 24.3.50; Latest build completely breaks my thumnail frames code

From: Drew Adams <[email-masked]>
Date: Fri, 13 Dec 2013 08:00:42 -0800 (PST)

>  >> Because that's what x_set_scroll_bar_width in frame.c does.
>  >> Unfortunately so, IMHO.
>  >
>  > Well, I don't understand, but maybe I do not need to.  Is that something
>  > new?  The regression is new.  If the C code has always done that, it has
>  > not been problematic for thumbnail frames before now.
> 
> You've been exploiting an undocumented feature, namely that setting the
> scrollbar width takes as reference values the numbers of lines and
> columns of a frame it had before an unacknowledged action preceding the
> current one.

That's one interpretation.

Actually, before Emacs on MS Windows changed so that the scroll bar did
not _automatically_ shrink with the font size, I did nothing at all to
the scroll bar.  Didn't have to.  In Emacs 20, shrinking the font is
sufficient to shrink the scroll bar as well.

To compensate for the fact that Emacs stopped shrinking the scroll bar
along with the font and frame, I added an explicit (user-configurable)
scroll-bar width for thumbified frames.  (And before I realized that that
workaround was possible I just eliminated the scroll bar in thumbified
frames for Emacs > 20.)

>  > You mean the only solution is to stop using Emacs 24 after 24.3?
> 
> If you insist on using the old code, maybe.

I don't insist on any particular code.  It's the behavior I'm after,
not a particular implementation.  Of course, if other things are
equal then I would prefer an implementation that works across Emacs
versions.  But as a start I'm just looking for an implementation that
works, i.e., a fix/workaround for the regression.

Stefan mentioned that I should not need to change my code for this
regression, that it is just an Emacs bug that needs to be fixed.  If
that is the case then so much the better.  But I am willing to change
my code as needed.  I just need to know what changes I need to make.

> You should try the solution I sketched in my other mail.

What solution was that?  Can you state it again, in the context of
the thumb-frm.el code?  I believe I've tried everything I saw suggested
here, but I'm open to a fix for my code, of course.  I've been asking
for it.  The last suggestion I recall was to change the order, and I
reported the problems that caused.