function popup(url,windowname,width,height,scrollbars,features) {
		width=(width)?width:screen.width/2;
		height=(height)?height:screen.height/2;
		scrollbars=(scrollbars)?scrollbars:'yes';
		var screenX = (screen.width/2 - width/2);
		var screenY = (screen.height/2 - height/2);
		var features= "width=" + width + ",height=" + height +",scrollbars=" + scrollbars + ",status=no";
		features += ",screenX=" + screenX + ",left=" + screenX;
		features += ",screenY=" + screenY + ",top=" + screenY;
		
		var mywin=window.open(url, windowname, features);
		if (mywin)
		mywin.focus();
		return mywin;
	}
	
	function checkPopup(){
		
		if($('#rebre').attr('value') == 1){ canvi = 0; }else{ canvi = 1; }
		$('#rebre').attr('value', canvi);
		
	}