Don't apply GTK fix to OSX as it causes a hang.

Fixes: lp:1841379
* https://bugs.launchpad.net/kicad/+bug/1841379

(cherry picked from commit de8f97be6b)

common/view/wx_view_controls.cpp

@@ -677,8 +677,11 @@ void WX_VIEW_CONTROLS::UpdateScrollbars()
         m_parentPanel->SetScrollbars( 1, 1, newRange.x, newRange.y, newScroll.x, newScroll.y, true );
         m_scrollPos = newScroll;
 
-        // Trigger a mouse refresh to get the canvas update in GTK (re-draws the scrollbars)
+#ifndef __APPLE__
+        // Trigger a mouse refresh to get the canvas update in GTK (re-draws the scrollbars).
+        // Note that this causes an infinite loop on OSX as it generates a paint event.
         refreshMouse();
+#endif
     }
 }