/**
 * Emulate HTML5 attribute `placeholder` for old stupid browsers
 * @author arty, see: http://habrahabr.ru/blogs/javascript/74363/#comment_2146745
 */
Object.extend(Form.Element.Methods, {
	/**
	* Set devault value for text input, it will disappear on focusing input
	* @param element target input
	* @param value given default value
	*/
	setDefaultValue: function(element, value) {
		element = $(element);
		value = value || element.readAttribute('placeholder');

		if (!value) return;

		var setDefault = function() {
			if (element.value.empty()) {
				element.value = value;
			}
		}

		function empty(){ 
			if (element.value == value) {
				element.value = ''; 
			}
		}

		setDefault();
		element.observe('blur', setDefault);
		element.observe('focus', empty);
		element.form && $(element.form).observe('submit', empty);

		return element;
	}
});