This paper describes the design and implementation of the user interface for a prototype immersive VRML2 browser, with particular reference to the planning and viewpoint movement aspects of navigation in the virtual environment.

Rather than being hard-coded in the browser, the user interface objects are part of the virtual environment itself (i.e. stored in the VRML scene graph). Advantages of this "first-class user interface" are described, and implications for an open, extensible approach to user interface evolution and browser implementation are considered.