bug#1176: redisplay bugs

[Glenn Morris]

> Redisplay goes horribly wrong when a before-string contains multiple
> display properties.
>
> Reproduce by evaluating this expression:
>
>   (let ((buf (get-buffer-create "foo")))
>     (with-current-buffer buf
>       (display-buffer buf)
>       (erase-buffer)
>       (dolist (o (overlays-in (point-min) (point-max)))
>         (delete-overlay o))
>       (insert "ABC")
>       (let ((o (make-overlay 2 3))
>             (s (make-string 5 ?X)))
>         (put-text-property 0 1 'display "1" s)
>         (put-text-property 1 2 'display "2" s)
>         (put-text-property 2 3 'display "3" s)
>         (put-text-property 3 4 'display "4" s)
>         (put-text-property 4 5 'display "5" s)
>         (overlay-put o 'display "Y")
>         (overlay-put o 'before-string s))))
>
> The correct behavior would be to see the buffer ?foo? pop up
> displaying the characters ?A12345YC?.  The horribly wrong behavior
> that actually happens is that redisplay of the buffer stops completely
> after ?A1? is shown.


This piece appears to be fixed in 22.2 and up.