As web applications evolves, their structure may become more and more complex. Thus, systematic approaches/methods for web application testing are needed. Existing methods take into consideration only those actions/events the user is prompted by the application itself, such as the selection of a hypertextual link or the submission of the data contained in a form. However, these methods do not consider also actions/events provided by the browser, such as the usage of backward and forward buttons, usage that in some cases may produce navigation inconsistencies. This paper proposes an approch to integrate existing testing techniques with a state-based testing devoted to discover possible inconsistencies caused by interactions with web browser buttons. A testing model, considering the role of the browser while navigating a web application, and some coverage criteria, are presented.