static JComponent gazelle_wavySpacer() {
  ret gazelle_wavySpacer(gazelle_color1(), gazelle_color2());
}

static JComponent gazelle_wavySpacer(Color color1, Color color2) {
  ret jMinWidth(30, swing(-> new JComponent {
    public void paintComponent(Graphics g) {
      cast g to Graphics2D;
      int w = getWidth(), h = getHeight();
  
      var points = graphAsPolygon(x -> 1-sineSigmoid(x), w, h);
      //printVars(+w, +h, points := takeFirst(5, points));
      fillRect(g, 0, 0, w, h, color2);
      fillPrecisePolygon(g, points, color1);
    }
  }));
}