Here is a simple static class, MouseButtonHelper, that offers a single method, IsDoubleClick,  to determine if a standard MouseLeftButtonDown or MouseLeftButtonUp event is a double click.  In the past I have used timers, and Triggers and Behaviors to accomplish the same thing, but this approach is less code, less XAML, and uses a lot less resources.

Usage is as follows:

  • In XAML or in code behind, handle the standard MouseLeftButtonDown or MouseLeftButtonUp event for the object you wish to perform double click handling.
  • Implement the handler function for the above event as follows: 
public void OnMouseButtonDown(object sender, MouseButtonEventArgs e)
{
	bool doubleClick = MouseButtonHelper.EventIsDoubleClick(sender, e);
	if (doubleClick)
		MessageBox.Show("Double click detected!", "Alert", MessageBoxButton.OK);
}

The code below has been tested and used with Silverlight 4.

using System;
using System.Windows;
using System.Windows.Input;

namespace ClassLibrary
{
	internal static class MouseButtonHelper
	{
		private const long k_DoubleClickSpeed = 500;
		private const double k_MaxMoveDistance = 10;

		private static long _LastClickTicks = 0;
		private static Point _LastPosition;
		private static WeakReference _LastSender;

		internal static bool IsDoubleClick(object sender, MouseButtonEventArgs e)
		{
			Point position = e.GetPosition(null);
			long clickTicks = DateTime.Now.Ticks;
			long elapsedTicks = clickTicks - _LastClickTicks;
			long elapsedTime = elapsedTicks / TimeSpan.TicksPerMillisecond;
			bool quickClick = (elapsedTime <= k_DoubleClickSpeed);
			bool senderMatch = (_LastSender != null && sender.Equals(_LastSender.Target));

			if (senderMatch && quickClick && position.Distance(_LastPosition) <= k_MaxMoveDistance)
			{
				// Double click!
				_LastClickTicks = 0;
				_LastSender = null;
				return true;
			}

			// Not a double click
			_LastClickTicks = clickTicks;
			_LastPosition = position;
			if (!quickClick)
				_LastSender = new WeakReference(sender);
			return false;
		}

		private static double Distance(this Point pointA, Point pointB)
		{
			double x = pointA.X - pointB.X;
			double y = pointA.Y - pointB.Y;
			return Math.Sqrt(x * x + y * y);
		}
	}
}