static JPanel gridLayoutPanel_trackWidth_evenlySpacedCols(final int cols) {
  ret customLayoutPanel_trackWidth(func(Container parent) {
    int gap = 10;
    Dimension size = parent.getSize();
    int w = max(100, size.width)-gap*2;
    int y = gap;
    LL<Component> rows = groupInFixedSizeRows(parent.getComponents(), cols);
    new L<Int> colWidths;
    for i to cols:
      colWidths.add((i+1)*w/cols-i*w/cols);
      
    for (L<Component> row : rows) {
      int h = 0, x = gap;
      for (Component c : row) h = max(h, c.getPreferredSize().height);
      for i over row: {
        row.get(i).setBounds(x, y, colWidths.get(i)-gap, h);
        x += colWidths.get(i);
      }
      y += h + gap;
    }
    
    ret componentsBoundingSize(parent, gap);
  });
}