code: public int getWidth(ViewNode node) {
  		int width = node.getDepth();
  		ViewNode children[] = node.findChildren();
  		for (int i = 0; i < children.length; i++) {
  			int current = getWidth(children[i]);
  			if (current > width)
  				width = current;
  		}
  		return (width);
  	}
docs: 该节点到树底端的距离 与node.getDepth()区别： 后者是该节点到树顶的距离。
  
  @param node
  @return