I wanted to capture the double click event, which is actually the MouseLeftButtonDown with the e.ClickCount ==2.

Since I transitioned to a new WPF project, handed off the Silverlight work, I have been trying to keep the same MVVM pattern. I wanted to get the double click off of my TreeViewItem so the child node could invoke the ViewModel to execute a Command.

Here is the behavior I wrote to handle this simple task.

Snippet

using System;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Controls.Primitives;
using System.Windows.Input;
using System.Windows.Controls;

namespace Seekford.Behaviors
{
    public static class MouseDoubleClickBehavior
    {
        /// <summary>
        /// Hooks up a weak event against the source Selectors MouseDoubleClick
        /// if the Selector has asked for the HandleDoubleClick to be handled
        ///�
        /// If the source Selector has expressed an interest in not having its
        /// MouseDoubleClick handled the internal reference
        /// </summary>
        private static void OnHandleDoubleClickCommandChanged(DependencyObject d,
            DependencyPropertyChangedEventArgs e)
        {
            FrameworkElement ele = d as FrameworkElement;
            if (ele != null)
            {
                ele.MouseLeftButtonDown -= OnMouseDoubleClick;
                if (e.NewValue != null)
                {
                    ele.MouseLeftButtonDown += OnMouseDoubleClick;
                }
            }
        }

        /// <summary>
        /// TheCommandToRun : The actual ICommand to run
        /// </summary>
        public static readonly DependencyProperty DoubleClickCommandProperty =
            DependencyProperty.RegisterAttached("DoubleClickCommand",
                typeof(ICommand),
                typeof(MouseDoubleClickBehavior),
                new FrameworkPropertyMetadata((ICommand)null,
                    new PropertyChangedCallback(OnHandleDoubleClickCommandChanged)));

        /// <summary>
        /// Gets the TheCommandToRun property. �
        /// </summary>
        public static ICommand GetDoubleClickCommand(DependencyObject d)
        {
            return (ICommand)d.GetValue(DoubleClickCommandProperty);
        }

        /// <summary>
        /// Sets the TheCommandToRun property. �
        /// </summary>
        public static void SetDoubleClickCommand(DependencyObject d, ICommand value)
        {
            d.SetValue(DoubleClickCommandProperty, value);
        }

        #region Handle the event

        /// <summary>
        /// Invoke the command we tagged.
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private static void OnMouseDoubleClick(object sender, MouseButtonEventArgs e)
        {
            //check for double clicks.
            if (e.ClickCount != 2)
                return;
            FrameworkElement ele = sender as FrameworkElement;

            DependencyObject originalSender = e.OriginalSource as DependencyObject;
            if (ele == null || originalSender == null)
                return;

            ICommand command = (ICommand)(sender as DependencyObject).GetValue(DoubleClickCommandProperty);

            if (command != null)
            {
                if (command.CanExecute(null))
                    command.Execute(null);
            }
        }
        #endregion
    }

}

Hopefully this helps you.

Oh, how to use. Almost forgot:

Snippet

xmlns:infraBehaviors="clr-namespace:Seekford.Behaviors;assembly=Seekford"

Snippet

 <Grid infraBehaviors:MouseDoubleClickBehavior.DoubleClickCommand="{Binding MyCommand}"  HorizontalAlignment="Stretch" >
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="Auto"/>       �
                </Grid.ColumnDefinitions>
                <Grid.RowDefinitions>
                    <RowDefinition></RowDefinition>
                </Grid.RowDefinitions>
                <TextBlock Text="{Binding Name}" TextWrapping="Wrap" FontWeight="Bold"  Grid.Column="0"  />
            </Grid>

Of course, make your own namespace and correct accordingly. But you already knew that.

Happy Coding!