Рисование мышкой в PictureBox

Насколько я знаю, PictureBox служит только для отображения картинок, а не рисования; для рукописного ввода/рисования служит класс InkPresenter. Код XAML:

<Canvas>
    <TextBlock Text="InkPresenter Control" FontWeight="Bold" Margin="50,30,0,0" />
    <Rectangle Height="500" Width="500" Margin="50,50,0,0" Stroke="Black" />
    <InkPresenter x:Name="MyIP" Height="500" Width="500"
        Margin="50,50,0,0"
        MouseLeftButtonDown="MyIP_MouseLeftButtonDown" 
        LostMouseCapture="MyIP_LostMouseCapture" 
        MouseMove="MyIP_MouseMove" 
        Background="Transparent" Opacity="1" />
</Canvas>

Код cs:

public Page()
{
    InitializeComponent();
    SetBoundary();
}
Stroke NewStroke;

// A new stroke object named MyStroke is created. 
// MyStroke is added to the StrokeCollection of the InkPresenter named MyIP
private void MyIP_MouseLeftButtonDown(object sender, MouseEventArgs e)
{
    MyIP.CaptureMouse();
    StylusPointCollection MyStylusPointCollection = new StylusPointCollection();
    MyStylusPointCollection.Add(e.StylusDevice.GetStylusPoints(MyIP));
    NewStroke = new Stroke(MyStylusPointCollection);
    MyIP.Strokes.Add(NewStroke);
}

//  StylusPoint objects are collected from the MouseEventArgs and added to MyStroke. 
private void MyIP_MouseMove(object sender, MouseEventArgs e)
{
    if (NewStroke != null)
        NewStroke.StylusPoints.Add(e.StylusDevice.GetStylusPoints(MyIP));
}

//  MyStroke is completed
private void MyIP_LostMouseCapture(object sender, MouseEventArgs e)
{
    NewStroke = null;        
}

//  Set the Clip property of the inkpresenter so that the strokes
//  are contained within the boundary of the inkpresenter
private void SetBoundary()
{
    RectangleGeometry MyRectangleGeometry = new RectangleGeometry();
    MyRectangleGeometry.Rect = new Rect(0, 0, MyIP.ActualWidth, MyIP.ActualHeight);
    MyIP.Clip = MyRectangleGeometry;
}