// START POP-UP AND CENTRE

function open_popup(url, winName, winWidth, winHeight, status, scrollbars, resizable) {
	window.open(url,winName,'toolbar=0,location=0,directories=0,status='+status+',menubar=0,scrollbars='+scrollbars+',resizable='+resizable+',left='+centre(winWidth,screen.availWidth)+',top='+centre(winHeight,screen.availHeight)+',width='+winWidth+',height='+winHeight);
}

function centre(size,area) {
	return (area/2)-(size/2);
}

// END POP-UP AND CENTRE



function are_you_sure() {
	if (confirm("Are you sure?")) {
		return true;
	} else {
		return false;
	}
}