code: private void paintColumnHeading(final WTableColumn col, final boolean sortable,
  			final WebXmlRenderContext renderContext) {
  		XmlStringBuilder xml = renderContext.getWriter();
  		int width = col.getWidth();
  		Alignment align = col.getAlign();
  
  		xml.appendTagOpen("ui:th");
  		xml.appendOptionalAttribute("width", width > 0, width);
  		xml.appendOptionalAttribute("sortable", sortable, "true");
  
  		if (Alignment.RIGHT.equals(align)) {
  			xml.appendAttribute("align", "right");
  		} else if (Alignment.CENTER.equals(align)) {
  			xml.appendAttribute("align", "center");
  		}
  
  		xml.appendClose();
  
  		col.paint(renderContext);
  
  		xml.appendEndTag("ui:th");
  	}
docs: Paints a single column heading.
  
  @param col the column to paint.
  @param sortable true if the column is sortable, false otherwise
  @param renderContext the RenderContext to paint to.