Testing Graphical User Interfaces (GUIs) is difficult, nvolving many states, inputs and events. We have previously reported a new method for testing GUIs that is scalable and concentrates on user sequences of GUI objects and selections that collaborate, called complete interaction sequences (CIS), and that produce the desired response for the user called the responsibility. In this paper we will extend this approach by investigating the use of memory tools to detect missing effects and CIS sequences, investigating interactions between CIS sequences, and providing empirical studies of five different GUI systems.