function addBodyLoadEventHandler(fn)
{

	//spg: warning - if this function is used in the head to
	//add a handler then be aware that also using the onload attribute in the
	//body tag will cause all registered handlers to be wipped clean

	if (typeof fn == 'string')
	{
		fn = new Function(fn);
	}
	var oldHandler = window.onload;
	if (!oldHandler)
	{

		window.onload = fn;
		return;
	}
	if (typeof oldHandler == 'string')
	{
		oldHandler = new Function(oldHandler);
	}

	window.onload = function()
						{
							if(oldHandler)
							{							

								oldHandler();
							}
							fn();							
						};
	return;
}

function getChildElements (el)
{
	//return a collection containing references to all element child nodes
	//optionally if an extra arg is passed it is treated as an element tag name selector
	var childElements = [];
	var j = 0;
	var childItem;
	var tag = "";	
	if (arguments.length > 1)
	{
		tag = arguments[1].toUpperCase();
	}
	for (var i = 0; i < el.childNodes.length; i++) {
		childItem = el.childNodes[i];
		if (childItem.nodeType == 1 && ((tag == "") ? childItem.tagName.toUpperCase() : tag) == childItem.tagName.toUpperCase()) {//ELEMENT_NODE = 1
				childElements[j] = childItem;
				j++;
		}
	}
	return childElements;	
}

/*
 * getNodesByType.js - Retreives nodes based on node type and filter function criteria
 *
 * Parameters:
 *      type: an integer (preferably a mnemonic constant from the W3C DOM Node class)
 *            representing the node's type.
 *    filter: a function returning a boolean indicating whether or not the node should
 *            be included in the results
 *
 * The following example gets all nodes in a document having a "class" attribute with
 * the value of "foo":
 *
 *  var nodes = document.getNodesByType(Node.ELEMENT_NODE, function(n) {
 *      return (n.className == "foo");
 *  });
 *
 * Written by Dave Lindquist (http://www.gazingus.org)
 * 6 April 2003
 */
 
function getElementsByFilter(element, filter)
{
	return getNodesByType(element,1,filter);
}
 
function getNodesByType(element,type, filter)
{
    var nodes = new Array();
    var context = element;
    var next;
    
    if (element.nodeType == null) return nodes;
    if (typeof filter != "function") filter = function() { return true; }
    
    while (context != null)
    {
        if (context.hasChildNodes())
        {
            context = context.firstChild;
        }
        else if (context != element && null != (next = context.nextSibling))
        {
            context = next;
        }
        else
        {
            next = null;
            for ( ; context != element; context = context.parentNode)
            {
                next = context.nextSibling;
                if (next != null) break;
            }
            context = next;
        }
        
        if (context != null && context.nodeType == type && filter(context))
        {
            nodes[nodes.length] = context;
        }
    }
    
    return nodes;
}

/* not sure this works in ie??
if (Node && Node.prototype)
    Node.prototype.getNodesByType = getNodesByType;
else
    Object.prototype.getNodesByType = getNodesByType;
*/