function toggleLayer(whichLayer)
	{
		var elem, vis;
		
		if( document.getElementById ) // this is the way the standards work
			elem = document.getElementById( whichLayer );
		else if( document.all ) // this is the way old msie versions work
			elem = document.all[whichLayer];
		else if( document.layers ) // this is the way nn4 works
			elem = document.layers[whichLayer];
	  	
		vis = elem.style;
	  
		// if the style.display value is blank we try to figure it out here
		if (vis.display=='' && elem.offsetWidth != undefined && elem.offsetHeight != undefined)
		{
			vis.display = (elem.offsetWidth != 0 && elem.offsetHeight != 0) ? 'block' : 'none';
		}
		
		vis.display = (vis.display=='' || vis.display=='block') ? 'none' : 'block';
	}
	
	
	function check_review_text(text, id)
	{
		if (document.getElementById(id) )
		{
			if (document.getElementById(id).value == text)
			{
				document.getElementById(id).value = '';
			}
			
		}
	}

	function matrix_highlight()
	{
		var fields = document.forms['cart_quantity'].elements;

		for ( var i = 0; i < fields.length; i++ ) 
		{
			if (fields[i].type == 'text')
			{
				current_value = parseInt(fields[i].value);
				
				if (current_value > 0)
				{
					fields[i].className = 'given_matrix_quantity_highlight';
				}
				else
				{
					fields[i].className = 'given_matrix_quantity';
				}
			}
		}
	}