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

[Eli Zaretskii]

> Date:  Wed, 25 Oct 2017 23:20:09 -0700
> From:  Keith David Bershatsky <esq@lawlist.com>
> Cc:  29002@debbugs.gnu.org
> 
> • hscrolling_current_line_p is true.
> • w->suspend_auto_hscroll is false.
> • w->hscroll > 0.
> • All non-current lines are also hscrolled.
> • it.first_visible_x == 0.
> 
> What would be a good method to programmatically test to see whether all other 
> lines are hscrolled given the above?

The above means that auto-hscroll is set to 'current-line'.  In this
case, the line that shows point is hscrolled by w->hscroll, and all
the other lines are hscrolled by w->min_hscroll (in units of the
frame's canonical character width).