I am very new to Selenium, so my apologies if it\'s a silly question.
I have successfully wired up IntelliJ (Play! framework) with Selenium, and created some tests using firefox
You can use FindElement(By.ClassName(//name of your class)); I would recommend that you either loop through and search the DOM for a set period of time or set a Thread.sleep(xxxx) and then look for the appended class.