bug#29002: it.first_visible_x is erroneously 0 while horizontal scrolling.

[Eli Zaretskii]

On November 5, 2017 11:15:41 AM GMT+02:00, Keith David Bershatsky 
<esq@lawlist.com> wrote:
> The new fix relating to #29002 has an unintended side-effect of
> causing a full redisplay too often, e.g., when using isearch.
> 
> I am uncertain why the current Emacs design sets
> w->suspend_auto_hscroll to *true* every command loop, but that is what
> causes the new condition to force a thorough redisplay much more often
> than is actually needed.
> 
> 
>         /* If the position of this window's point has explicitly
>            changed, no more suspend auto hscrolling.  */
>         if (w->suspend_auto_hscroll
>             && NILP (Fequal (Fwindow_point (window),
>                              Fwindow_old_point (window))))
>           {
> 
> AUTO_STRING (my_string_one, "Hello world!");
> CALLN (Fmessage, my_string_one);
> 
>             w->suspend_auto_hscroll = false;
>             /* Force thorough redisplay of this window, to show the
>                effect of disabling hscroll suspension immediately.  */
>             SET_FRAME_GARBAGED (XFRAME (w->frame));
>           }

Please describe a recipe where you see suspend_auto_hscroll being
set true every command loop.