The Vrui VR toolkit aims to support fully scalable and portable applications that run on a range of VR environments starting from a laptop with a touchpad, over desktop environments with special input devices such as space balls, to full-blown immersive VR environments ranging from a single-screen workbench to a multi-screen tiled display wall or CAVE. Applications using the Vrui VR toolkit are written without a particular input environment in mind, and Vrui-enabled VR environments are configured to map the available input devices to application functions such that the application appears to be written natively for the environment it runs on. For example, a Vrui application running on the desktop should be as usable and intuitive as a 3D application written specifically for the desktop.