Render Ido suggestions using an overlay

* lisp/ido.el (ido--overlay): New variable.
(ido-exhibit): Render with 'after-string' on an overlay
(bug#38457).

Author: dgutov

lisp/ido.el

@@ -4492,6 +4492,8 @@ For details of keybindings, see `ido-find-file'."
 	(ido-tidy))
       (throw 'ido contents))))
 
+(defvar ido--overlay nil)
+
 (defun ido-exhibit ()
   "Post command hook for Ido."
   ;; Find matching files and display a list in the minibuffer.
@@ -4726,7 +4728,13 @@ For details of keybindings, see `ido-find-file'."
 	(let ((inf (ido-completions contents)))
 	  (setq ido-show-confirm-message nil)
 	  (ido-trace "inf" inf)
-	  (insert inf))
+          (when ido--overlay
+            (delete-overlay ido--overlay))
+          (let ((o (make-overlay (point-max) (point-max) nil t t)))
+            (when (> (length inf) 0)
+              (put-text-property 0 1 'cursor t inf))
+            (overlay-put o 'after-string inf)
+            (setq ido--overlay o)))
 	))))
 
 (defun ido-completions (name)