Event.observe(window, 'load', function() {
	Event.observe($('user.username'),'keyup', function() {
		if( this.value.length > 4 ) {
			
			var url = '';
			
			if( typeof current_user != 'undefined' ) {
				url = '/user/account/username_available/'+this.value+'/'+current_user;
			} else {
				url = '/user/account/username_available/'+this.value;
			}
			
			RemoteCall.execute(url, function(data) {
	  		if( data.available ) {
	  			$('username_availability_message').style.visibility='hidden';
	  		} else {
	  			$('username_availability_message').style.visibility='visible';
	  		}
	  	});
	  }
	}.bindAsEventListener($('user.username')));
	
});