<Window.TaskbarItemInfo>
    <TaskbarItemInfo x:Name="taskBarItemInfo1" 
                     Overlay="{StaticResource ResourceKey=StopImage}"
                     ThumbnailClipMargin="80,0,80,140"
                     Description="Taskbar Item Info Sample">
        <TaskbarItemInfo.ThumbButtonInfos>
            <ThumbButtonInfoCollection>
                <ThumbButtonInfo
                    DismissWhenClicked="False"
                    Command="MediaCommands.Play"
                    CommandTarget="{Binding ElementName=btnPlay}"
                    Description="Play"
                    ImageSource="{StaticResource ResourceKey=PlayImage}"/>
                <ThumbButtonInfo
                    DismissWhenClicked="True"
                    Command="MediaCommands.Stop"
                    CommandTarget="{Binding ElementName=btnStop}"
                    Description="Stop"
                    ImageSource="{StaticResource ResourceKey=StopImage}"/>
            </ThumbButtonInfoCollection>
        </TaskbarItemInfo.ThumbButtonInfos>
    </TaskbarItemInfo>
</Window.TaskbarItemInfo>

<Window x:Class="Shell_TaskbarItemSample.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:Shell_TaskbarItemSample"
        Title="MainWindow" Height="300" Width="300" Icon="app.ico">
    <Window.Resources>
        <DrawingImage x:Key="PlayImage">
            <DrawingImage.Drawing>
                <DrawingGroup>
                    <DrawingGroup.Children>
                        <GeometryDrawing Brush="Green" Geometry="F1 M 50,25L 0,0L 0,50L 50,25 Z "/>
                    </DrawingGroup.Children>
                </DrawingGroup>
            </DrawingImage.Drawing>
        </DrawingImage>
        <DrawingImage x:Key="StopImage">
            <DrawingImage.Drawing>
                <DrawingGroup>
                    <DrawingGroup.Children>
                        <GeometryDrawing Brush="Gray" Geometry="F1 M 0,0L 50,0L 50,50L 0,50L 0,0 Z "/>
                    </DrawingGroup.Children>
                </DrawingGroup>
            </DrawingImage.Drawing>
        </DrawingImage>
    </Window.Resources>
    <Window.CommandBindings>
        <CommandBinding Command="MediaCommands.Play"
                  Executed="StartCommand_Executed"
                  CanExecute="StartCommand_CanExecute"/>
        <CommandBinding Command="MediaCommands.Stop"
                  Executed="StopCommand_Executed"
                  CanExecute="StopCommand_CanExecute"/>
    </Window.CommandBindings>
    <Window.TaskbarItemInfo>
        <TaskbarItemInfo x:Name="taskBarItemInfo1" 
                         Overlay="{StaticResource ResourceKey=StopImage}"
                         ThumbnailClipMargin="80,0,80,140"
                         Description="Taskbar Item Info Sample">
            <TaskbarItemInfo.ThumbButtonInfos>
                <ThumbButtonInfoCollection>
                    <ThumbButtonInfo
                        DismissWhenClicked="False"
                        Command="MediaCommands.Play"
                        CommandTarget="{Binding ElementName=btnPlay}"
                        Description="Play"
                        ImageSource="{StaticResource ResourceKey=PlayImage}"/>
                    <ThumbButtonInfo
                        DismissWhenClicked="True"
                        Command="MediaCommands.Stop"
                        CommandTarget="{Binding ElementName=btnStop}"
                        Description="Stop"
                        ImageSource="{StaticResource ResourceKey=StopImage}"/>
                </ThumbButtonInfoCollection>
            </TaskbarItemInfo.ThumbButtonInfos>
        </TaskbarItemInfo>
    </Window.TaskbarItemInfo>

    <Grid>
        <StackPanel>
            <TextBlock x:Name="tbCount" FontSize="72" HorizontalAlignment="Center"/>
            <StackPanel Orientation="Horizontal">
                <Button x:Name="btnPlay" Content="Play" Command="MediaCommands.Play" />
                <Button x:Name="btnStop" Content="Stop" Command="MediaCommands.Stop" />
            </StackPanel>    
        </StackPanel>
    </Grid>
</Window>

// MainWindow.xaml.cs
using System.ComponentModel;
using System.Windows;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Shell;

namespace Shell_TaskbarItemSample
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        private BackgroundWorker _backgroundWorker = new BackgroundWorker();

        public MainWindow()
        {
            InitializeComponent();

            // Set up the BackgroundWorker.
            this._backgroundWorker.WorkerReportsProgress = true;
            this._backgroundWorker.WorkerSupportsCancellation = true;
            this._backgroundWorker.DoWork += new DoWorkEventHandler(bw_DoWork);
            this._backgroundWorker.ProgressChanged += new ProgressChangedEventHandler(bw_ProgressChanged);
            this._backgroundWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bw_RunWorkerCompleted);
        }

        private void StartCommand_CanExecute(object sender, CanExecuteRoutedEventArgs e)
        {
            e.CanExecute = true;
            e.Handled = true;
        }

        private void StartCommand_Executed(object sender, ExecutedRoutedEventArgs e)
        {
            if (this._backgroundWorker.IsBusy == false)
            {
                this._backgroundWorker.RunWorkerAsync();
                // When the task is started, change the ProgressState and Overlay
                // of the taskbar item to indicate an active task.
                this.taskBarItemInfo1.ProgressState = TaskbarItemProgressState.Normal;
                this.taskBarItemInfo1.Overlay = (DrawingImage)this.FindResource("PlayImage");
            }
            e.Handled = true;
        }

        private void StopCommand_CanExecute(object sender, CanExecuteRoutedEventArgs e)
        {
            e.CanExecute = this._backgroundWorker.WorkerSupportsCancellation;
            e.Handled = true;
        }

        private void StopCommand_Executed(object sender, ExecutedRoutedEventArgs e)
        {
            this._backgroundWorker.CancelAsync();
            e.Handled = true;
        }

        void bw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            // When the task ends, change the ProgressState and Overlay
            // of the taskbar item to indicate a stopped task.
            if (e.Cancelled == true)
            {
                // The task was stopped by the user. Show the progress indicator
                // in the paused state.
                this.taskBarItemInfo1.ProgressState = TaskbarItemProgressState.Paused;
            }
            else if (e.Error != null)
            {
                // The task ended with an error. Show the progress indicator
                // in the error state.
                this.taskBarItemInfo1.ProgressState = TaskbarItemProgressState.Error;
            }
            else
            {
                // The task completed normally. Remove the progress indicator.
                this.taskBarItemInfo1.ProgressState = TaskbarItemProgressState.None;
            }
            // In all cases, show the 'Stopped' overlay.
            this.taskBarItemInfo1.Overlay = (DrawingImage)this.FindResource("StopImage");
        }

        void bw_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            this.tbCount.Text = e.ProgressPercentage.ToString();
            // Update the value of the task bar progress indicator.
            this.taskBarItemInfo1.ProgressValue = (double)e.ProgressPercentage / 100;
        }

        void bw_DoWork(object sender, DoWorkEventArgs e)
        {        
            BackgroundWorker _worker = sender as BackgroundWorker;
            if (_worker != null)
            {
                for (int i = 1; i <= 100; i++)
                {
                    if (_worker.CancellationPending == true)
                    {
                        e.Cancel = true;
                        break;
                    }
                    else
                    {
                        System.Threading.Thread.Sleep(25);
                        _worker.ReportProgress(i);
                    }
                }
            }
        }

    }   
}