Actions class for mouseover?

I want to mousover in order to click a menu item that appears. I read开发者_StackOverflow社区 about the Actions class to use

Actions builder = new Actions(driver);

However it doesn't work for me because I get type or namespace not found. I am importing

using System;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading;
using NUnit.Framework;
using OpenQA.Selenium;
using OpenQA.Selenium.Firefox;

You need to add

using OpenQA.Selenium.Interactions;

to your import list. It's a little surprising that Visual Studio's Intellisense didn't pick this up for you, but that should get you on your way.