If all the ids and classes are assigned during run-time, you're kinda SOL. Though Selenium does support other locator strategies like XPath, and even plain old

If all the ids and classes are assigned during run-time, you're kinda SOL. Though Selenium does support other locator strategies like XPath, and even plain old JavaScript expressions to find an element. I would ask the the ExtJS folks how they would expect someone to test their app from a GUI perspective. You need some kind of reliable handle to find an element on the page so you can act on it.