Question about align-to behaviour with wrap-mode

[Abdul-Lateef Haji-Ali via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org>]

I noticed what I think is strange behaviour with `:align-to` that I am wondering if it's intended and if there's a way of achieving a desired behaviour.

To reproduce in an `emacs -Q`, just run this:

(progn
   (toggle-word-wrap +1)
   (goto-char (point-max))
   (insert
    (concat "\n\n"
            (make-string (- (window-width) 3) 69)
            " "
            (propertize " " 'display
                        `(space :align-to (- right
                                             10)))
            "After\n\n")))

The word 'After' is not aligned to `(- right 10)` because the text before is too long. Instead "After" is displayed at the beginning of the next line (or broken across two lines if toggle-word-wrap is disabled) and the alignment is ignored.

If I execute instead

(progn
   (toggle-word-wrap +1)
   (goto-char (point-max))
   (insert
    (concat "\n\n"
            (make-string (window-width) 69)
            " "
            (propertize " " 'cursor 1 'display
                        `(space :align-to (- right
                                             10)))
            "After\n\n")))
            
the alignment is "correct" on the second line.

In both situation, I was intending (and expecting) the word "After" to be on the second line and to be correctly aligned at (- right 10). Is the current behaviour intended? Is there a way to achieve my desired behaviour?

I could of course add spaces before the right-aligned text, but then if more text is added I would need to adjust the spaces dynamically which is less-than-ideal.

-- Al

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