Modes, Quasimodes and the iPhone
Modes cause issues if they make computers behave in unexpected ways. However, if the modes themselves are obvious to the user, if it is always clear how to exit the current mode, and if the modes interfere with as few of the user’s actions as possible, these issues disappear. In some cases, modes may even be preferable to quasimodes or to a non-modal interface.
Lukas Mathis
Indeed, many applications would scarcely be possible at all without modes. Any application with a tool palette—Adobe’s entire Creative Suite, for instance—will usually treat its tools as modes. Choose the Marquee tool and you’re in Marquee Selection mode until you choose something else.
The trick in Adobe’s case was to switch the mouse cursor to a graphic reflecting the current mode. Since the cursor is generally the focal point of a user’s interaction, it’s hard not to notice that your mouse’s normal arrow cursor is suddenly a crosshair, or a paint bucket, or whatever.
iPhone’s modal text selection is good because it’s very obvious when it’s active and there’s no consequence to forgetting: tap elsewhere on the screen and the mode disappears. iPhone photo touch-up and painting applications don’t fare so well: without a cursor and often without a visible tool palette, it’s too easy to forget you’re in Giant Red Paintbrush Mode. Thankfully most of these apps have Undo.