Use natural and intuitive affordances
Provide natural affordances as interaction mechanisms wherever
possible. Handles and other grasping surfaces provide immediate
visual cues that most users will recognize. Keep the interactions
simple, such as a single mouse click, and avoid real world
controls that are difficult to emulate using the input devices
provided. For example, rotating controls such as knobs and dials
are difficult to map to the x/y movement of a pointing device
such as a mouse.
The Realphone
uses a thumb indentation and arrows to indicate the tray handle. A simple
click on the handle slides the tray out providing accesses to the notebook.