(posn-col-row): Do something useful for scroll bar event.

1 files changed, 19 insertions, 9 deletions

diff --git a/lisp/subr.el b/lisp/subr.el
index b5b7a8d620d..c281a64843d 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -420,17 +420,27 @@ POSITION should be a list of the form
 as returned by the `event-start' and `event-end' functions."
   (nth 2 position))
 
-(defsubst posn-col-row (position)
-  "Return the column and row in POSITION, measured in characters.
+(defun posn-col-row (position)
+  "Return the row and column in POSITION, measured in characters.
 POSITION should be a list of the form
    (WINDOW BUFFER-POSITION (X . Y) TIMESTAMP)
-as returned by the `event-start' and `event-end' functions."
-  (let* ((pair (nth 2 position))
-         (window (posn-window position))
-         (frame (if (framep window) window (window-frame window)))
-         (x (/ (car pair) (frame-char-width frame)))
-         (y (/ (cdr pair) (frame-char-height frame))))
-    (cons x y)))
+as returned by the `event-start' and `event-end' functions.
+For a scroll-bar event, the result column is 0, and the row
+corresponds to the vertical position of the click in the scroll bar."
+  (let ((pair   (nth 2 position))
+        (window (posn-window position)))
+    (if (eq (if (symbolp (nth 1 position)) (nth 1 position)
+              (car (nth 1 position)))
+            'vertical-scroll-bar)
+        (cons 0 (scroll-bar-scale pair (1- (window-height window))))
+      (if (eq (if (symbolp (nth 1 position)) (nth 1 position)
+                (car (nth 1 position)))
+              'horizontal-scroll-bar)
+          (cons (scroll-bar-scale pair (window-width window)) 0)
+        (let ((frame (if (framep window) window (window-frame window)))
+              (x (/ (car pair) (frame-char-width frame)))
+              (y (/ (cdr pair) (frame-char-height frame))))
+          (cons x y))))))
 
 (defsubst posn-timestamp (position)
   "Return the timestamp of POSITION.