function captcha_refresh() {
	YAHOO.util.Connect.asyncRequest('POST', '/Main/captchaRefresh', captcha_refresh_callback, null);
}

var captcha_refresh_callback = {
		success:function(obj) {
			document.getElementById("captcha_data").innerHTML = obj.responseText;
		},
		failure:function(obj) {
			alert("Failed to refresh the image. Response: " + obj.responseText);
		}
};