clear space
Affordance
Use natural and intuitive affordances

hand grip imageProvide 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.

RealPhone tray affordanceThe 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.