sclass G22SnPSelector > MetaWithChangeListeners is Swingable {
  settable new SnPSettings settings;
  
  // show powers of two in pixelRows selector or all numbers?
  settableWithVar bool powerOfTwoPixelRows = true;
  
  settable int maxPixelRows = 512;
  
  SnPSettings get() { ret settings; }

  cachedVisualize {
    var colors = jspinner(settings.colors, 2, 256);
    main onChange(colors, -> {
      settings.colors = intFromSpinner(colors);
      change();
    });
    
    var pixelRows = jListSpinner(pixelRowsList(), settings.pixelRows);
    main onChange(pixelRows, -> {
      settings.pixelRows = intFromSpinner(pixelRows);
      change();
    });
    
    varPowerOfTwoPixelRows().onChange(->
      spinnerSetNumberList(pixelRows, pixelRowsList());

    var menuItem = jLiveValueCheckBoxMenuItem("Only show powers of two", varPowerOfTwoPixelRows());
    swing {
      new JPopupMenu menu;
      menu.add(menuItem);
      pixelRows.setComponentPopupMenu(menu);
    }
    
    ret hstack(
      colors,
      jlabel(" colors @ "),
      pixelRows,
      jlabel(" p"));
  }
  
  L<Int> pixelRowsList() {
    ret powerOfTwoPixelRows
      ? powersOfTwoUpTo(maxPixelRows)
      : virtualCountList_incl(1, maxPixelRows);
  }
}