code: private void addFlatSelectExample() {
  		add(new WHeading(HeadingLevel.H3, "WCheckBoxSelect with flat layout"));
  		add(new ExplanatoryText("Setting the layout to FLAT will make thecheck boxes be rendered in a horizontal line. They will wrap when they reach"
  				+ " the edge of the parent container."));
  		final WCheckBoxSelect select = new WCheckBoxSelect("australian_state");
  		select.setToolTip("Make a selection");
  		select.setButtonLayout(WCheckBoxSelect.LAYOUT_FLAT);
  		add(select);
  	}
docs: WCheckBoxSelect layout options These examples show the various ways to lay out the options in a WCheckBoxSelect
  NOTE: the default (if no buttonLayout is set) is LAYOUT_STACKED. adds a WCheckBoxSelect with LAYOUT_FLAT