Capturing meaningful interactions between a user and an application is useful. A meaningful interaction is an interaction that causes a change in state of one of the participants. Meaningful interaction capture is well established for console based applications. No techniques exist that capture only the meaningful interactions with a graphical interface. Data collected by such a system could be used for a variety of applications, such as HCI studies, authorship identification, cognitive modelling and screen recording. A methodology for capturing the meaningful interactions between a user and a graphical application is described. An implementation of this methodology has been developed, together with a supporting tool-set. A new corpus consisting of captured interactions between users and two applications with contrasting graphical interfaces has been collected and published. This corpus is analysed and used for authorship attribution.