Added code for erasing the small square between scrollbars.

Corrected window size if scrollbars is removed/added.
  Reduce flicker in scrollbars.
  Prevent scrollbars from jumping back to original position
    if the mouse just barely left the scrollbar.


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@14872 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/univ/winuniv.cpp

@@ -843,8 +843,12 @@ void wxWindow::SetScrollbar(int orient,
     // give the window a chance to relayout
     if ( hasClientSizeChanged )
     {
+#if wxUSE_TWO_WINDOWS
+        wxWindowNative::SetSize( GetSize() );
+#else
         wxSizeEvent event(GetSize());
         (void)GetEventHandler()->ProcessEvent(event);
+#endif
     }
 }