private void OnEnterNow( EnterNowEventArgs e )
 {
     if( EnterNow != null ) EnterNow( this, e );
 }
        private void OnEnterNow( object sender, EnterNowEventArgs e )
        {
            PanelViewModel p = (PanelViewModel)sender;
            DockPanel dp = _dockPanels[e.CurrentPosition];

            if( dp != null )
            {
                dp.Children.Add( new GridZone( e.Panel ) );
                e.Panel.ExitNode += OnExit;
            }
        }