[margin-path] Tentative fix for background clean-up

ace-window.el

@@ -401,12 +401,13 @@ LEAF is (PT . WND)."
             (goto-char (+ pt 1))
             (push (cons wnd old-pt) aw--windows-points)))
         ;; this is where we would need to add a display-margin thingie
-        (overlay-put ol 'before-string
-                     (propertize "." 'display
-                                 `((margin left-margin)
-                                   ,(propertize
-                                     (concat " " (aw--overlay-str wnd pt path))
-                                     'face (if (window-minibuffer-p wnd) 'aw-minibuffer-leading-char-face 'aw-leading-char-face)))))
+        (let ((str-margin (concat " " (aw--overlay-str wnd pt path))))
+              (add-face-text-property 0 (length str-margin) `(:background ,(face-attribute 'default :background)) nil str-margin)
+              (overlay-put ol 'before-string
+                           (propertize "." 'display
+                                       `((margin left-margin)
+                                         ,(propertize str-margin
+                                                      'face (if (window-minibuffer-p wnd) 'aw-minibuffer-leading-char-face 'aw-leading-char-face))))))
         (overlay-put ol 'window wnd)
         (push ol avy--overlays-lead)))))