Weird shape resizing behavior in WPF

Answer 1

Hello, I'm ending up answering my own question :)

I think the problem was here:

protected override System.Windows.Media.Geometry DefiningGeometry
{
    get
    {
        StreamGeometry geometry = new StreamGeometry();
        using (StreamGeometryContext context = geometry.Open())
        {
            context.BeginFigure(Points[0], false, true);
            foreach (Point pt in Points)
            {
                context.LineTo(pt, true, true);
            }
            geometry.Freeze();
            return geometry;
        }
    }
}

I switched to using PathGeometry & LineSegments and it works fine now.