function controlBlind(opt) {
		if(opt=='draw') {
			document.write('<div style="position:absolute;left:0px;bottom:0px;width:100%;height:100%;background-color:#ffffff;z-index:1" id="blind">&nbsp;</div>');
		}
		if(opt=='erase') {
			//document.getElementById('blind').style.display='none';
			scaleBlind = window.setInterval("controlBlind('diff')", 1);
		}
		if(opt=='diff') {
			with(document.getElementById('blind').style) {
			 	if(width=='100%') {
					n = 100;
			 	}
	     	n -= 5;
	     
	     	if(n<=0) {
			  	window.clearInterval(scaleBlind);
					display='none';
			 	} else {
			  	width  = n +'%';
			  	height = n +'%';
			 	}
			}
		}
	}