Behavior 클래스를 먼저 작성한다. public static class ScrollToSelectedBehavior { public static readonly DependencyProperty SelectedValueProperty = DependencyProperty.RegisterAttached( "SelectedValue", typeof(object), typeof(ScrollToSelectedBehavior), new PropertyMetadata(null, OnSelectedValueChange)); public static void SetSelectedValue(DependencyObject source, object value) { source.SetValue(SelectedValue..