1 files changed, 28 insertions, 8 deletions

diff --git a/src/macterm.c b/src/macterm.c
index a46c9cbbda4..2d03c8918c5 100644
--- a/src/macterm.c
+++ b/src/macterm.c
@@ -5071,6 +5071,7 @@ x_scroll_bar_create (w, top, left, width, height, disp_top, disp_height)
 #ifdef MAC_OSX
   bar->fringe_extended_p = Qnil;
 #endif
+  bar->redraw_needed_p = Qnil;
 #ifdef USE_TOOLKIT_SCROLL_BARS
   bar->track_top = Qnil;
   bar->track_height = Qnil;
@@ -5287,14 +5288,24 @@ XTset_vertical_scroll_bar (w, portion, whole, position)
       BLOCK_INPUT;
 
       /* If already correctly positioned, do nothing.  */
-      if (!(XINT (bar->left) == sb_left
-            && XINT (bar->top) == top
-            && XINT (bar->width) == sb_width
-            && XINT (bar->height) == height
+      if (XINT (bar->left) == sb_left
+          && XINT (bar->top) == top
+          && XINT (bar->width) == sb_width
+          && XINT (bar->height) == height
 #ifdef MAC_OSX
-            && !NILP (bar->fringe_extended_p) == fringe_extended_p
+          && !NILP (bar->fringe_extended_p) == fringe_extended_p
 #endif
-            ))
+          )
+        {
+          if (!NILP (bar->redraw_needed_p))
+            {
+#if USE_CG_DRAWING
+              mac_prepare_for_quickdraw (f);
+#endif
+              Draw1Control (SCROLL_BAR_CONTROL_REF (bar));
+            }
+        }
+      else
         {
           /* Since toolkit scroll bars are smaller than the space reserved
              for them on the frame, we have to clear "under" them.  */
@@ -5336,6 +5347,8 @@ XTset_vertical_scroll_bar (w, portion, whole, position)
   bar->fringe_extended_p = fringe_extended_p ? Qt : Qnil;
 #endif
 
+  bar->redraw_needed_p = Qnil;
+
 #ifdef USE_TOOLKIT_SCROLL_BARS
   if (NILP (bar->track_top))
     {
@@ -5693,8 +5706,15 @@ void
 x_scroll_bar_clear (f)
      FRAME_PTR f;
 {
-  XTcondemn_scroll_bars (f);
-  XTjudge_scroll_bars (f);
+  Lisp_Object bar;
+
+  /* We can have scroll bars even if this is 0,
+     if we just turned off scroll bar mode.
+     But in that case we should not clear them.  */
+  if (FRAME_HAS_VERTICAL_SCROLL_BARS (f))
+    for (bar = FRAME_SCROLL_BARS (f); VECTORP (bar);
+         bar = XSCROLL_BAR (bar)->next)
+      XSCROLL_BAR (bar)->redraw_needed_p = Qt;
 }