* nsterm.m (ns_set_vertical_scroll_bar): Don't call bar setPosition: unless

needed (Bug#18757).

Fixes: debbugs:18993

src/ChangeLog

@@ -3,6 +3,8 @@
 	* nsterm.m (init): Replace OSX 10.9 check with IMPL_COCOA.
 	(run): Ditto.  Only use non-system event loop if OSX version is
 	exactly 10.9 (Bug#18993).
+	(ns_set_vertical_scroll_bar): Don't call bar setPosition: unless
+	needed (Bug#18757).
 
 2014-11-07  Michael Albinus  <michael.albinus@gmx.de>
 

src/nsterm.m

@@ -3802,6 +3802,7 @@ overwriting cursor (usually when cursor on a tab) */
   int top, left, height, width, sb_width, sb_left;
   EmacsScroller *bar;
   BOOL fringe_extended_p;
+  BOOL update_p = YES;
 
   /* optimization; display engine sends WAY too many of these.. */
   if (!NILP (window->vertical_scroll_bar))
@@ -3816,6 +3817,7 @@ overwriting cursor (usually when cursor on a tab) */
             }
           else
             view->scrollbarsNeedingUpdate--;
+          update_p = NO;
         }
     }
 
@@ -3869,6 +3871,7 @@ overwriting cursor (usually when cursor on a tab) */
 
       bar = [[EmacsScroller alloc] initFrame: r window: win];
       wset_vertical_scroll_bar (window, make_save_ptr (bar));
+      update_p = YES;
     }
   else
     {
@@ -3881,10 +3884,12 @@ overwriting cursor (usually when cursor on a tab) */
           if (oldRect.origin.x != r.origin.x)
               ns_clear_frame_area (f, sb_left, top, width, height);
           [bar setFrame: r];
+          update_p = YES;
         }
     }
 
-  [bar setPosition: position portion: portion whole: whole];
+  if (update_p)
+    [bar setPosition: position portion: portion whole: whole];
   unblock_input ();
 }