public class GoRulerCursor 

public class TriangleCursor : GoRulerCursor {
  public TriangleCursor() {
    this.Size = new Size(10, 20);
    this.ForeColor = Color.Blue;
    this.BackColor = Color.LightBlue;
  }
            
  public override void Paint(Graphics g, GoRuler ruler, float measure) {
    Pen p = new Pen(this.ForeColor, 0);
    Brush b = new SolidBrush(this.BackColor);
            
    Rectangle r = ruler.DisplayRectangle;
    float left = measure - this.Width/2.0f;
    float right = measure + this.Width/2.0f;
            
    PointF[] pts;
    if (ruler.Orientation == Orientation.Horizontal)
      pts = new PointF[] {new PointF(left, r.Y), new PointF(right, r.Y), new PointF(measure, r.Bottom)};
    else
      pts = new PointF[] {new PointF(r.X, left), new PointF(r.X, right), new PointF(r.Right, measure)};
            
    g.FillPolygon(b, pts);
    g.DrawPolygon(p, pts);
            
    b.Dispose();
    p.Dispose();
  }
}