void InkCanvas_PreviewMouseDown(object sender, MouseEventArgs e)
{
    InkCanvas ic = (InkCanvas)sender;
    
    Point pt = e.GetPosition(ic);

    // If the user is moving selected strokes, prepare the strokes to be
    // moved to another InkCanvas.
    if (ic.HitTestSelection(pt) == 
        InkCanvasSelectionHitResult.Selection)
    {
        StrokeCollection selectedStrokes = ic.GetSelectedStrokes();
        StrokeCollection strokesToMove = selectedStrokes.Clone();
    
        // Remove the offset of the selected strokes so they
        // are positioned when the strokes are dropped.
        Rect inkBounds = strokesToMove.GetBounds();
        TranslateStrokes(strokesToMove, -inkBounds.X, -inkBounds.Y);
        
        // Perform drag and drop.
        MemoryStream ms = new MemoryStream();
        strokesToMove.Save(ms);
        DataObject dataObject = new DataObject(
            StrokeCollection.InkSerializedFormat, ms);
        
        DragDropEffects effects = 
            DragDrop.DoDragDrop(ic, dataObject, 
                                DragDropEffects.Move);

        if ((effects & DragDropEffects.Move) == 
             DragDropEffects.Move)
        {
            // Remove the selected strokes 
            // from the current InkCanvas.
            ic.Strokes.Remove(selectedStrokes);
        }
    }
}