User Control

Users should have the feeling that they control the computer and not vice versa (Apple Computer Macintosh Human Interface Guidelines 9, Microsoft 3-4). Nevertheless, there are situations in which a software "takes care" of the user, offering only those alternatives that are judged "good" for the user or that "protect" the user from having to make detailed decisions (Apple Computer Macintosh Human Interface Guidelines 9). As a result, a balance has to be created which provides users with as much control as possible and as little constraint as needed. This corresponds to what has been said in section 3.1.4; the operating system protects a user from the complexity of a system but enables him to rely on abstractions.
In Microsoft's Guidelines, the authors also put emphasis on the user's option to customize aspects of the interface and the need for software which is as interactive and responsible as possible (4).
Users should always be able to undo an action, at least the last step, which is called the principle of forgiveness (Apple Computer Macintosh Human Interface Guidelines 10, Microsoft 6). Users should also be able to stop running processes (see Figure 4 for an example; the copy process is stopped by the user when he hits the "Cancel" button³⁸). User Control is closely related to a system's feedback.