WPFTreeViewItemTestControl.xaml の相互作用ロジック
Inheritance: System.Windows.Controls.UserControl
        static WPFTreeViewItemTestControl Init(Grid grid)
        {
            WPFTreeViewItemTestControl ctrl = new WPFTreeViewItemTestControl();

            grid.Children.Add(ctrl);
            return(ctrl);
        }
 static WPFTreeViewItemTestControl Init(Grid grid)
 {
     WPFTreeViewItemTestControl ctrl = new WPFTreeViewItemTestControl();
     grid.Children.Add(ctrl);
     return ctrl;
 }