Event.addBehavior({

	'.auto-clear:focus' : function(event) {
		if (! this.default_value) {
			this.default_value = this.value;
		}
		if (this.value == this.default_value) {
			this.value = "";
		}
	},

	'.auto-clear:blur': function(event) {
		if(this.value == "") {
			this.value = this.default_value;
		}
	}

});