Show the overlay in the bottom of the window too

This is useful when point overlaps the overlay at the top of the
window, making it difficult to read the label.

Fixes #129.
Fixes #132.

ace-window.el

@@ -138,6 +138,13 @@ Its value is a (width . height) pair in pixels or nil for the default frame size
 (0 . 0) is special and means make the frame size the same as the last selected frame size."
   :type '(cons integer integer))
 
+(defcustom aw-char-position 'top-left
+  "Window positions of the character overlay.
+Consider changing this if the overlay tends to overlap with other things."
+  :type '(choice
+          (const :tag "top left corner only" 'top-left)
+          (const :tag "both left corners" 'left)))
+
 ;; Must be defined before `aw-make-frame-char' since its :set function references this.
 (defvar aw-dispatch-alist
   '((?x aw-delete-window "Delete Window")
@@ -264,6 +271,35 @@ Modify them back eventually.")
           (delete-region (point-min) (point-max))))))
   (setq aw-empty-buffers-list nil))
 
+(defun aw--overlay-str (wnd pos path)
+  "Return the replacement text for an overlay in WND at POS,
+accessible by typing PATH."
+  (let ((old-str (or
+                  (ignore-errors
+                    (with-selected-window wnd
+                      (buffer-substring pos (1+ pos))))
+                  "")))
+    (concat
+     (cl-case aw-leading-char-style
+       (char
+        (string (avy--key-to-char (car (last path)))))
+       (path
+        (mapconcat
+         (lambda (x) (string (avy--key-to-char x)))
+         (reverse path)
+         ""))
+       (t
+        (error "Bad `aw-leading-char-style': %S"
+               aw-leading-char-style)))
+     (cond ((string-equal old-str "\t")
+            (make-string (1- tab-width) ?\ ))
+           ((string-equal old-str "\n")
+            "\n")
+           (t
+            (make-string
+             (max 0 (1- (string-width old-str)))
+             ?\ ))))))
+
 (defun aw--lead-overlay (path leaf)
   "Create an overlay using PATH at LEAF.
 LEAF is (PT . WND)."
@@ -273,38 +309,30 @@ LEAF is (PT . WND)."
         (push (current-buffer) aw-empty-buffers-list)
         (let ((inhibit-read-only t))
           (insert " ")))
+
       (let* ((pt (car leaf))
-             (ol (make-overlay pt (1+ pt) (window-buffer wnd)))
-             (old-str (or
-                       (ignore-errors
-                         (with-selected-window wnd
-                           (buffer-substring pt (1+ pt))))
-                       ""))
-             (new-str
-              (concat
-               (cl-case aw-leading-char-style
-                 (char
-                  (string (avy--key-to-char (car (last path)))))
-                 (path
-                  (mapconcat
-                   (lambda (x) (string (avy--key-to-char x)))
-                   (reverse path)
-                   ""))
-                 (t
-                  (error "Bad `aw-leading-char-style': %S"
-                         aw-leading-char-style)))
-               (cond ((string-equal old-str "\t")
-                      (make-string (1- tab-width) ?\ ))
-                     ((string-equal old-str "\n")
-                      "\n")
-                     (t
-                      (make-string
-                       (max 0 (1- (string-width old-str)))
-                       ?\ ))))))
+             (ol (make-overlay pt (1+ pt) (window-buffer wnd))))
+        (overlay-put ol 'display (aw--overlay-str wnd pt path))
         (overlay-put ol 'face 'aw-leading-char-face)
         (overlay-put ol 'window wnd)
-        (overlay-put ol 'display new-str)
-        (push ol avy--overlays-lead)))))
+        (push ol avy--overlays-lead))
+
+      (when (eq aw-char-position 'left)
+        (let* ((pt
+                (save-excursion
+                  ;; Move to the start of the last visible line in the buffer.
+                  (move-to-window-line -1)
+                  (move-beginning-of-line nil)
+                  ;; If this line is empty, use the previous line so we
+                  ;; have space for the overlay.
+                  (when (equal (point) (point-max))
+                    (previous-line))
+                  (point)))
+               (ol (make-overlay pt (1+ pt) (window-buffer wnd))))
+          (overlay-put ol 'display (aw--overlay-str wnd pt path))
+          (overlay-put ol 'face 'aw-leading-char-face)
+          (overlay-put ol 'window wnd)
+          (push ol avy--overlays-lead))))))
 
 (defun aw--make-backgrounds (wnd-list)
   "Create a dim background overlay for each window on WND-LIST."