bug#16348: 24.3.50; Increasing internal-border-width cuts menubar and toolbar on non-toolkit builds

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sun, 05 Jan 2014 18:59:29 +0100
> From: martin rudalics <rudalics@gmx.at>
> CC: mituharu@math.s.chiba-u.ac.jp, 16348@debbugs.gnu.org
> 
>  >> The only practical solution I usually see is to resize the frame to
>  >> some other size and size it back.  I doubt that this is the same as
>  >> resetting the enabled_p flags.
>  >
>  > What do you think it does, in addition?  It reallocates the glyph
>  > matrices to fit the new dimensions, which clears that flag.
>  >
>  > Anyway, I'm not aware of any mechanism in the display engine to avoid
>  > redrawing portions of the screen, except the one that compares glyph
>  > rows.  All the other redisplay optimizations are suppressed by setting
>  > windows_or_buffers_changed, and I imagine you already do that.
>  >
>  > If I'm wrong, can you point to the code that avoids redrawing those
>  > parts?
> 
> If things were that easy I wouldn't have bothered you.  Take the
> scenario from bug 14222:
> 
> (progn
>    (set-frame-parameter (selected-frame) 'scroll-bar-width 6)
>    (sit-for 1)
>    (set-frame-parameter (selected-frame) 'left-fringe 27)
>    (sit-for 1)
>    (set-frame-parameter (selected-frame) 'scroll-bar-width 6)
>    (sit-for 1))
> 
> I have inserted windows_or_buffers_changed settings all over
> x_set_scroll_bar_width with no avail.  But when I subsequently re-resize
> the frame, it gets drawn correctly.

I meant if I'm wrong about disabling the current matrix's rows.