protected override Gdk.Rectangle OnMouseMove (Context g, Color strokeColor, ImageSurface surface, int x, int y, int lastX, int lastY) { double cx = Math.Round (x / 100.0) * 100.0; double cy = Math.Round (y / 100.0) * 100.0; double dx = (cx - x) * 10.0; double dy = (cy - y) * 10.0; for (int i = 0; i < 50; i++) { g.MoveTo (cx, cy); g.QuadraticCurveTo ( x + Random.NextDouble () * dx, y + Random.NextDouble () * dy, cx, cy); g.Stroke (); } return Gdk.Rectangle.Zero; }