private void registerChangeListeners(Proxy oldSelection, Proxy selection) {
if (oldSelection != null && oldSelection instanceof BeanProxy) {
Proxy type = ((BeanProxy)
oldSelection).getPropertyProxy(PolicyModel.CONTENT);
type.removeListener(changeListener);
}
if (selection != null && selection instanceof BeanProxy) {
Proxy type = ((BeanProxy)
selection).getPropertyProxy(PolicyModel.CONTENT);