Very simples canvas dashboard in WPF

Dashboard.cs

public partial class MainWindow : Window
{
    private Line line = null;
    private Brush oldBrush; 
    public MainWindow()
    {
        InitializeComponent();
    }

    void onDragDelta(object sender, DragDeltaEventArgs e)
    {
        line = new Line { Stroke = Brushes.Black, StrokeThickness = 1 };

        var element = sender as Thumb;

        line.X1 = Canvas.GetLeft(element);
        line.X2 = line.X1 + e.HorizontalChange;
        Canvas.SetLeft(element, Canvas.GetLeft(element) +
                                e.HorizontalChange);


        line.Y1 = Canvas.GetTop(element) + 15;
        line.Y2 = line.Y1 + e.VerticalChange;
        Canvas.SetTop(element, Canvas.GetTop(element) +
                                e.VerticalChange);

        this.myCanvasStretch.Children.Add(line);
    }

    void onDragStarted(object sender, DragStartedEventArgs e)
    {
        var element = sender as Thumb;
        oldBrush = element.Background;
        element.Background = Brushes.DarkGray;
    }
    void onDragCompleted(object sender, DragCompletedEventArgs e)
    {
        line = null;
        var element = sender as Thumb;
        element.Background = oldBrush;
    }
}