Using GTK+ with HTML5 3 GTK Library Using GTK+ with HTML5 HTML-specific aspects of using GTK+ The GDK Broadway backend provides support for displaying GTK+ applications using HTML5 and Web sockets. To run your application in this way, select the Broadway backend by setting GDK_BACKEND=broadway. Then you can make your application appear in a web browser by pointing it at http://127.0.0.1:8080. Note that you need to enable web sockets in your web browser. You can choose a different port from the default 8080 by setting the BROADWAY_DISPLAY environment variable to the port that you want to use.