(mouse-drag-vertical-line): Handle left-side scroll bars.

1 files changed, 38 insertions, 26 deletions

diff --git a/lisp/mouse.el b/lisp/mouse.el
index d760c437bf7..6f4a60a86ec 100644
--- a/lisp/mouse.el
+++ b/lisp/mouse.el
@@ -306,12 +306,18 @@ This command must be bound to a mouse click."
         (start-event-window (car (car (cdr start-event))))
         (start-nwindows (count-windows t))
         (old-selected-window (selected-window))
-        event mouse x left right edges wconfig growth)
+        event mouse x left right edges wconfig growth
+        (which-side
+         (or (cdr (assq 'vertical-scroll-bars default-frame-alist))
+             'left)))
     (if (one-window-p t)
         (error "Attempt to resize sole ordinary window"))
-    (if (= (nth 2 (window-edges start-event-window))
-           (frame-width start-event-frame))
-        (error "Attempt to drag rightmost scrollbar"))
+    (if (eq which-side 'left)
+        (if (= (nth 0 (window-edges start-event-window)) 0)
+            (error "Attempt to drag leftmost scrollbar"))
+      (if (= (nth 2 (window-edges start-event-window))
+             (frame-width start-event-frame))
+          (error "Attempt to drag rightmost scrollbar")))
     (track-mouse
       (progn
         ;; enlarge-window only works on the selected window, so
@@ -349,28 +355,34 @@ This command must be bound to a mouse click."
                 ((null (car (cdr mouse)))
                  nil)
                 (t
-                 (setq x (car (cdr mouse))
-                       edges (window-edges)
-                       left (nth 0 edges)
-                       right (nth 2 edges))
-                 ;; scale back a move that would make the
-                 ;; window too thin.
-                 (cond ((< (- x left -1) window-min-width)
-                        (setq x (+ left window-min-width -1))))
-                 ;; compute size change needed
-                 (setq growth (- x right -1)
-                       wconfig (current-window-configuration))
-                 (enlarge-window growth t)
-                 ;; if this window's growth caused another
-                 ;; window to be deleted because it was too
-                 ;; thin, rescind the change.
-                 ;;
-                 ;; if size change caused space to be stolen
-                 ;; from a window to the left of this one,
-                 ;; rescind the change.
-                 (if (or (/= start-nwindows (count-windows t))
-                         (/= left (nth 0 (window-edges))))
-                     (set-window-configuration wconfig)))))))))
+                 (save-selected-window
+                   ;; If the scroll bar is on the window's left,
+                   ;; adjust the window on the left.
+                   (if (eq which-side 'left)
+                       (select-window (previous-window)))
+                   (setq x (- (car (cdr mouse))
+                              (if (eq which-side 'left) 2 0))
+                         edges (window-edges)
+                         left (nth 0 edges)
+                         right (nth 2 edges))
+                   ;; scale back a move that would make the
+                   ;; window too thin.
+                   (if (< (- x left -1) window-min-width)
+                       (setq x (+ left window-min-width -1)))
+                   ;; compute size change needed
+                   (setq growth (- x right -1)
+                         wconfig (current-window-configuration))
+                   (enlarge-window growth t)
+                   ;; if this window's growth caused another
+                   ;; window to be deleted because it was too
+                   ;; thin, rescind the change.
+                   ;;
+                   ;; if size change caused space to be stolen
+                   ;; from a window to the left of this one,
+                   ;; rescind the change.
+                   (if (or (/= start-nwindows (count-windows t))
+                           (/= left (nth 0 (window-edges))))
+                       (set-window-configuration wconfig))))))))))
 
 (defun mouse-set-point (event)
   "Move point to the position clicked on with the mouse.