<Window x:Class="sxCoordinateDesktop.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        WindowStyle="None" AllowsTransparency="True" Background="Transparent"
        WindowState="Maximized" Name="win"               
        MouseMove="win_MouseMove" 
        MouseLeftButtonDown="win_MouseLeftButtonDown" 
        MouseLeftButtonUp="win_MouseLeftButtonUp">
 
    <Window.ContextMenu>
        <ContextMenu>
            <StackPanel>
                <MenuItem Header="Exit" Click="MenuItemExit_Click" />
                <Rectangle Height="1" Fill="Black"/>
                <MenuItem Header="(c)2009 Biggle" Click="MenuItemBiggle_Click"/>
            </StackPanel>
        </ContextMenu>
    </Window.ContextMenu>    
 
    <Canvas Name="AppicationCanvas" Background="AliceBlue" Opacity="0.5" Cursor="Cross" 
            MouseMove="Canvas_MouseMove">
        <TextBlock FontSize="25" Name="txtBoxCoordinate" Width="300" />
    </Canvas>
 
</Window>

using System.Diagnostics;
using System.Windows;
using System.Windows.Controls;
using MouseEventArgs = System.Windows.Input.MouseEventArgs;
 
namespace sxCoordinateDesktop
{
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
        }
 
        private Point click;
        private void win_MouseMove(object sender, MouseEventArgs e)
        {
            this.Left += e.GetPosition(this).X - click.X;
            this.Top += e.GetPosition(this).Y - click.Y;
        }
 
        private void win_MouseLeftButtonDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
        {
            click = new Point(e.GetPosition(this).X, e.GetPosition(this).Y);
            win.WindowState = WindowState.Normal;
        }
 
        private void Canvas_MouseMove(object sender, MouseEventArgs e)
        {
            txtBoxCoordinate.Text = e.GetPosition(this).ToString();
            txtBoxCoordinate.SetValue(Canvas.LeftProperty, e.GetPosition(this).X);
            txtBoxCoordinate.SetValue(Canvas.TopProperty, e.GetPosition(this).Y);
        }
 
        private void MenuItemExit_Click(object sender, RoutedEventArgs e)
        {
            Close();
        }
 
        private void MenuItemBiggle_Click(object sender, RoutedEventArgs e)
        {
            Process.Start("http://www.biggle.de");
        }
 
        private void win_MouseLeftButtonUp(object sender, System.Windows.Input.MouseButtonEventArgs e)
        {
            win.WindowState = WindowState.Maximized;
        }
 
    }
}