fix a bug of layer changes.  see :http://code.google.com/p/svg-edit/issues/detail?id=1099
fix a bug of layer changes. 
see :http://code.google.com/p/svg-edit/issues/detail?id=1099
Gisellameloni/svg-edit,Gisellameloni/svg-edit,Gisellameloni/svg-edit,Gisellameloni/svg-edit