Using the Z-Axis in User Interfaces for Head Mountable Displays

Methods, apparatus, and computer-readable media are described herein related to a user interface (UI) for a computing device, such as a head-mountable device (HMD). The computing device can detect a communication event. In response to the communication event, the computing device can display a first item having a current size on a display associated with a display plane. A hand-movement input device associated with the computing device can receive a first input indicative of a gesture toward the display plane. In response to receiving the first input, the computing device can display a first change to the current size of the first item. The hand-movement input device can receive a second input indicative of a gesture away from the display plane. In response to the second input, the computing device can display a second change to the current size of the first item.