bug#7474: In latest source, icomplete-mode makes cursor disappear in minibuffer

[Fran <flitterio@gmail.com>]

I wrote:

> Using Emacs built from the latest source on Windows 7, the cursor
> can be made to disappear as follows:
> 
> 1. Start Emacs with: emacs -Q
> 
> 2. Type: ESC ESC : (icomplete-mode 1) RET C-h v desc
> 
> 3. The cursor is no longer visisble in the minibuffer.
> 
> 4. Type: C-b
> 
> 5. The cursor is visible over the letter 'c' in "desc".
> 
> 6. Type: C-f
> 
> 7. The cursor is once again no longer visible.
> 
> This is acting like some of the text in the minibuffer has the
> 'intangible property, but the word "intangible" doesn't appear anywhere
> in lisp/icomplete.el.

I think this has to do with the use of the 'cursor text property in this code in
src/icomplete.el (slightly elided for readability):

(defun icomplete-exhibit ()
  ...
  (when (and icomplete-mode (icomplete-simple-completing-p))
    (save-excursion
      (goto-char (point-max))
                                        ; Insert the match-status information:
      (if (and (> (point-max) (minibuffer-prompt-end))
               buffer-undo-list         ; Wait for some user input.
               ...)
          (let ((text (...)
                (buffer-undo-list t)
                deactivate-mark)
            ;; Do nothing if while-no-input was aborted.
            (when (stringp text)
              (move-overlay icomplete-overlay (point) (point) (current-buffer))
              ;; The current C cursor code doesn't know to use the overlay's
              ;; marker's stickiness to figure out whether to place the cursor
              ;; before or after the string, so let's spoon-feed it the pos.
              (put-text-property 0 1 'cursor t text)
              (overlay-put icomplete-overlay 'after-string text)))))))