docs: private Widget makeKeyPanel() {
      final Grid grid = new Grid(5, 5);
      addKeyRadioButton(grid, 0, 0, "out left top");
      addKeyRadioButton(grid, 0, 2, "out center top");
      addKeyRadioButton(grid, 0, 4, "out right top");
      addKeyRadioButton(grid, 1, 1, "top left");
      addKeyRadioButton(grid, 1, 2, "top center");
      addKeyRadioButton(grid, 1, 3, "top right").setValue(true);
      addKeyRadioButton(grid, 2, 0, "out center left");
      addKeyRadioButton(grid, 2, 1, "center left");
      addKeyRadioButton(grid, 2, 2, "center");
      addKeyRadioButton(grid, 2, 3, "center right");
      addKeyRadioButton(grid, 2, 4, "out center right");
      addKeyRadioButton(grid, 3, 1, "bottom left");
      addKeyRadioButton(grid, 3, 2, "bottom center");
      addKeyRadioButton(grid, 3, 3, "bottom right");
      addKeyRadioButton(grid, 4, 0, "out bottom left");
      addKeyRadioButton(grid, 4, 2, "out bottom center");
      addKeyRadioButton(grid, 4, 4, "out bottom right");
      final Grid.CellFormatter cf = grid.getCellFormatter();
      cf.getElement(1, 1).getStyle().setProperty("borderLeft", "1px solid #000");
      cf.getElement(1, 1).getStyle().setProperty("borderTop", "1px solid #000");
      cf.getElement(1, 2).getStyle().setProperty("borderTop", "1px solid #000");
      cf.getElement(1, 3).getStyle().setProperty("borderTop", "1px solid #000");
      cf.getElement(1, 3).getStyle().setProperty("borderRight", "1px solid #000");
      cf.getElement(2, 1).getStyle().setProperty("borderLeft", "1px solid #000");
      cf.getElement(2, 3).getStyle().setProperty("borderRight", "1px solid #000");
      cf.getElement(3, 1).getStyle().setProperty("borderLeft", "1px solid #000");
      cf.getElement(3, 1).getStyle().setProperty("borderBottom", "1px solid #000");
      cf.getElement(3, 2).getStyle().setProperty("borderBottom", "1px solid #000");
      cf.getElement(3, 3).getStyle().setProperty("borderBottom", "1px solid #000");
      cf.getElement(3, 3).getStyle().setProperty("borderRight", "1px solid #000");
      final VerticalPanel vbox = new VerticalPanel();
      vbox.add(new InlineLabel("Key location:"));
      vbox.add(grid);
      vbox.add(horizontalkey);
      keybox.setValue(true);
      vbox.add(keybox);
      vbox.add(nokey);
      return vbox;
    }