Navigating applications using side-mounted touchpad

1. A method comprising:

by a computing device, detecting a touch event on a side-mounted touchpad of the computing device during display of a current user interface of an application executing on the computing device, wherein the application comprises a navigation hierarchy that comprises a home user-interface layer, a plurality of sub user-interface layers, and a plurality of user-interface branches;

by the computing device, determining a particular sub user-interface layer and user-interface branch that the current user interface corresponds to;

by the computing device, if the touch event is a forward lateral flick event and there is a next user-interface layer in the particular user-interface branch of the current user interface, then navigating to the next user-interface layer in the particular user-interface branch of the current user interface; and

by the computing device, if the touch event is a backward lateral flick event and there is a previous sub user-interface layer in the particular user-interface branch of the current user interface, then navigating to the previous user-interface layer in the particular user-interface branch of the current user interface.

2. The method of claim 1 , further comprising if the touch event is a tap event, then navigating directly to the home user-interface layer.

3. The method of claim 1 , wherein the application is a web browser.

4. The method of claim 1 , wherein the application is an operating system.

5. The method of claim 1 , wherein the side-mounted touchpad comprises a concave surface.

6. An device comprising:

a display;

a side-mounted touchpad;

one or more processors; and

a memory coupled to the processors comprising instructions executable by the processors, the processors being operable when executing the instructions to:

detect a touch event on the side-mounted touchpad of the device during display of a current user interface of an application executing on the computing device, wherein the application comprises a navigation hierarchy that comprises a home user-interface layer, a plurality of sub user-interface layers, and a plurality of user-interface branches;

determine a particular sub user-interface layer and user-interface branch that the current user interface corresponds to;

if the touch event is a forward lateral flick event and there is a next user-interface layer in the particular user-interface branch of the current user interface, then navigate to the next user-interface layer in the particular user-interface branch of the current user interface; and

by the computing device, if the touch event is a backward lateral flick event and there is a previous sub user-interface layer in the particular user-interface branch of the current user interface, then navigating to the previous user-interface layer in the particular user-interface branch of the current user interface.

7. The device of claim 6 , wherein the processors are further operable when executing the instructions to if the touch event is a tap event, then navigate directly to the home user-interface layer.

8. The device of claim 6 , wherein the display is a touch screen.

9. The device of claim 6 , wherein the side-mounted touchpad comprises a concave surface.

10. The device of claim 6 , wherein the application is a web browser.

11. The device of claim 6 , wherein the application is an operating system.

12. One or more computer-readable non-transitory storage media embodying software that is operable when executed to:

detect a touch event on a side-mounted touchpad of the computing device during display of a current user interface of an application executing on the computing device, wherein the application comprises a navigation hierarchy that comprises a home user-interface layer, a plurality of sub user-interface layers, and a plurality of user-interface branches;

determine a particular sub user-interface layer and user-interface branch that the current user interface corresponds to;

if the touch event is a forward lateral flick event and there is a next user-interface layer in the particular user-interface branch of the current user interface, then navigate to the next user-interface layer in the particular user-interface branch of the current user interface; and

if the touch event is a backward lateral flick event and there is a previous sub user-interface layer in the particular user-interface branch of the current user interface, then navigate to the previous user-interface layer in the particular user-interface branch of the current user interface.

13. The media of claim 12 , wherein the software is further operable when executed to if the touch event is a tap event, then navigate directly to the home user-interface layer.

14. The media of claim 12 , wherein the application is a web browser.

15. The media of claim 12 , wherein the application is an operating system.

16. The media of claim 12 , wherein the side-mounted touchpad comprises a concave surface.