An applet module defines a class that is instantiated by the browser when the applet is invoked.
Applets interact with the user by creating one or more Tk widgets.
If you see this, your browser does not support Python applets. Grail must be able to find the Question class in the module file Question.py . By default, the module name and the class name are assumed to be the same. Thus, it is possible to have an applet displayed by Grail but an image displayed by other browsers. As far as we know, Grail is the first browser to implement this tag.