HAT IDEAS

- svg-of-character
  but alignment and styling are hard then

- hack emacs C code to allow overlaying svgs on characters
  not clear how practical this is.

- OVERLAYS BEFORE EACH LINE
  see also: https://www.gnu.org/software/emacs/manual/html_node/elisp/Line-Height.html
  https://www.gnu.org/software/emacs/manual/html_node/elisp/Special-Properties.html
  see line-height, line-spacing, line-prefix

- negative width spaces?
  https://www.gnu.org/software/emacs/manual/html_node/elisp/Specified-Space.html

(defun put-before-line ()
  (interactive)
  (clear-overlays)
  (let* ((pos (save-excursion (beginning-of-line) (point)))
         (overlay (make-overlay pos pos))
         (face '(;(:height 120)
                 (:background "lightgrey")))
         (text (copy-sequence "x\n"))
         (image (let* ((w (window-font-width))
                       (svg (svg-create w w)))
                  (svg-circle svg 0 0 w)
                  (svg-image svg :scale 1))))
    (message "%s" image)
    (put-text-property 0 (length text) 'face face text)
    (put-text-property 0 (length text) 'line-height t text)
    (put-text-property 0 1 'display image text)
    (overlay-put overlay 'cursorless t)
    (overlay-put overlay 'before-string text)))