WPF HTML Supported TextBlock

/*
 * Created by SharpDevelop.
 * User: LYCJ
 * Date: 19/10/2007
 * Time: 2:53
 * 
 * To change this template use Tools | Options | Coding | Edit Standard Headers.
 */

using System;
using System.Collections.Generic;

namespace QuickZip.MiniHtml2
{
	/// <summary>
	/// Represent owner of all HtmlTag.
	/// </summary>
	public class HtmlTagTree : HtmlTagNode
	{
		public HtmlTagTree() : base(null, null)
		{
			isRoot = true;
			tag = new HtmlTag("master","");
		}
		
		public override bool CanAdd(HtmlTag aTag)
		{
			return true;
		}		
		
		static string printNode(Int32 level, HtmlTagNode node)
		{
			string spacing = " ";
			string retVal = "";
			for (int i = 0; i < level; i++)
				spacing += "  ";
			
			retVal += spacing + node.ToString() + '\r'+'\n';
			
			foreach (HtmlTagNode subnode in node)
				retVal += HtmlTagTree.printNode(level+1, subnode);			
			
			return retVal;
		}
		
		public override string ToString()
		{
			string retVal = "";
			
			foreach (HtmlTagNode subnode in this)
				retVal += HtmlTagTree.printNode(0, subnode);
			
			return retVal;
		}
	}
}