code: private void paintChildrenWithConstraint(
  			final List<Duplet<WComponent, BorderLayoutConstraint>> children,
  			final WebXmlRenderContext renderContext, final BorderLayoutConstraint constraint) {
  		String containingTag = null;
  		XmlStringBuilder xml = renderContext.getWriter();
  
  		final int size = children.size();
  
  		for (int i = 0; i < size; i++) {
  			Duplet<WComponent, BorderLayoutConstraint> child = children.get(i);
  
  			if (constraint.equals(child.getSecond())) {
  				if (containingTag == null) {
  					containingTag = getTag(constraint);
  					xml.appendTag(containingTag);
  				}
  
  				child.getFirst().paint(renderContext);
  			}
  		}
  
  		if (containingTag != null) {
  			xml.appendEndTag(containingTag);
  		}
  	}
docs: Paints all the child components with the given constraint.
  
  @param children the list of potential children to paint.
  @param renderContext the RenderContext to paint to.
  @param constraint the target constraint.