for(i=0;i<document.styleSheets.length;i++)
{
	if(''.concat(document.styleSheets[i].href).indexOf('dcss')>-1)
	{
		var rules = document.styleSheets[i].rules||document.styleSheets[i].cssRules
		window.real_rules = new Array();
		for(r=0;r<rules.length;r++)
		{
			if(''.concat(rules[r].selectorText).indexOf('medium')>-1)
			{
				window.real_rules.push(rules[r]);
			}
		}
	}
}
function change_bk()
{
	window.currentFrame = window.currentFrame||0;
	window.currentFrame=((window.real_rules.length-1)<window.currentFrame)?0:window.currentFrame;
	document.getElementById('background_pane').className = window.real_rules[window.currentFrame].selectorText.split('.')[1];
	window.currentFrame=window.currentFrame+1;
	clearTimeout(window.timerObj);
	window.timerObj = setTimeout("change_bk()", 1000*5 );
}