avy.el (avy--overlay-at-full): Improve

Re #51

avy.el

@@ -556,19 +556,20 @@ LEAF is normally ((BEG . END) . WND)."
          (beg (if (consp (car leaf))
                   (caar leaf)
                 (car leaf)))
-         (wnd (cdr leaf)))
+         (wnd (cdr leaf))
+         oov)
     (when (or avy-highlight-first (> (length str) 1))
       (set-text-properties 0 1 '(face avy-lead-face-0) str))
     (with-selected-window wnd
       (save-excursion
         (goto-char beg)
-        (when (cl-some (lambda (o)
-                         (and (eq (overlay-get o 'category) 'avy)
-                              (eq (overlay-get o 'window) wnd)))
-                       (overlays-in (point) (min (+ (point) len)
-                                                 (line-end-position))))
-          (setq str (substring str 0 1))
-          (setq len 1))
+        (when (setq oov (cl-find-if (lambda (o)
+                                      (and (eq (overlay-get o 'category) 'avy)
+                                           (eq (overlay-get o 'window) wnd)))
+                                    (overlays-in (point) (min (+ (point) len)
+                                                              (line-end-position)))))
+          (setq len (- (overlay-start oov) beg))
+          (setq str (substring str 0 len)))
         (let ((other-ov (cl-find-if
                          (lambda (o)
                            (and (eq (overlay-get o 'category) 'avy)