code: private void buildConfigOptions() {
  		WFieldLayout layout = new WFieldLayout(WFieldLayout.LAYOUT_STACKED);
  		layout.setMargin(new Margin(null, null, Size.LARGE, null));
  		layout.addField("Select a WPanel Type", panelType);
  		contentField = layout.addField("Panel content", panelContent);
  		headingField = layout.addField("heading", tfHeading);
  		showMenuField = layout.addField("Show menu", showMenu);
  		showUtilBarField = layout.addField("Show utility bar", showUtilBar);
  		layout.addField((WLabel) null, applyConfigButton);
  		add(layout);
  	}
docs: Set up the UI for the configuration options.