The Graphical User Interfaces (GUIs) of software products are extensively used by researchers and practitioners in Software Engineering field. For Example, they are used for testing, measuring usability, and many other purposes. This paper describes a new reverse engineering approach to transform the GUI into class diagram. However, the correctness of such transformation process is essential for the corrected execution of the overall software. To assure this correctness, the interpreted Petri nets models will be implemented on the proposed transformation processes (i.e. capturing, normalization, and translation processes)