Use WXUNUSED and give more explaination for the handler

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@55055 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/listctrl.cpp

@@ -2880,9 +2880,11 @@ void wxListMainWindow::HighlightAll( bool on )
     }
 }
 
-void wxListMainWindow::OnChildFocus(wxChildFocusEvent& event)
+void wxListMainWindow::OnChildFocus(wxChildFocusEvent& WXUNUSED(event))
 {
-    // do nothing
+    // Do nothing here.  This prevents the default handler in wxScrolledWindow
+    // from needlessly scrolling the window when the edit control is
+    // dismissed.  See ticket #9563.
 }
 
 void wxListMainWindow::SendNotify( size_t line,