MouseDownBehavior WPF

using System;
using System.Diagnostics;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;

namespace UI.Behaviors
{
    /// <summary>
    /// Behavoir to handle elements Mouse Down Event
    /// <remarks>
    /// bhv:MouseDownBehavior.Command="{Binding MouseDownCommand}"
    /// bhv:MouseDownBehavior.UsePreviewMouseDown="True"
    /// </remarks>
    /// </summary>
    public static class MouseDownBehavior
    {
        #region Command Dependency Property

        public static readonly DependencyProperty CommandProperty = DependencyProperty.RegisterAttached(
            "Command",
            typeof(ICommand),
            typeof(MouseDownBehavior),
            new UIPropertyMetadata(null, OnCommandChanged));


        public static ICommand GetCommand(DependencyObject obj)
        {
            return (ICommand)obj.GetValue(CommandProperty);
        }

        public static void SetCommand(DependencyObject obj, ICommand value)
        {
            obj.SetValue(CommandProperty, value);
        }
        #endregion

        #region UsePreviewMouseDown Dependency Property

        public static readonly DependencyProperty UsePreviewMouseDownProperty = DependencyProperty.RegisterAttached(
            "UsePreviewMouseDown",
            typeof(bool),
            typeof(MouseDownBehavior),
            new UIPropertyMetadata(false));


        public static bool GetUsePreviewMouseDown(DependencyObject obj)
        {
            return (bool)obj.GetValue(UsePreviewMouseDownProperty);
        }

        public static void SetUsePreviewMouseDown(DependencyObject obj, bool value)
        {
            obj.SetValue(UsePreviewMouseDownProperty, value);
        }
        #endregion

        static void OnCommandChanged(DependencyObject sender, DependencyPropertyChangedEventArgs args)
        {
            var ele = sender as UIElement;
            if (ele == null)
                return;

            if (args.OldValue != null)
            {
                if (GetUsePreviewMouseDown(ele))
                    ele.PreviewMouseDown -= OnMouseDown;
                else
                    ele.MouseDown -= OnMouseDown;
            }

            if (args.NewValue != null)
            {
                if (GetUsePreviewMouseDown(ele))
                    ele.PreviewMouseDown += OnMouseDown;
                else
                    ele.MouseDown += OnMouseDown;
            }
        }

        static void OnMouseDown(object sender, MouseButtonEventArgs e)
        {
            var ele = sender as UIElement;
            if (ele == null)
                return;

            var command = GetCommand(ele);
            if (command != null)
            {
                if (command.CanExecute(e))
                {
                    command.Execute(e);
                }
            }
        }
    }
}