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Direct Manipulation and WYSIWYG

As pointed out in section 2.2.2, the concept of direct manipulation was born in the 1960s. Users should feel that they are directly controlling the objects represented by the computer; thus, the results of an operation have to be made visible immediately (Apple Computer Macintosh Human Interface Guidelines 5).
The WYSIWYG principle (What You See Is What You Get) is closely related to the concept of direct manipulation. According to the WYSIWYG principle, printed output should not differ from what the user sees on the screen (Apple Computer Macintosh Human Interface Guidelines 9, Helander 123).
Finally, modelessness relates to the concept of direct manipulation. While every application can be regarded as a mode, the principle of modelessness refers to modes in applications. The UNIX editor vi is a good example of a program working with modes, having an "edit" and a "command" mode. In this case, a mode restricts the user's options. However, there are different types of modes, which are acceptable according to Apple Computer's Guidelines (12):

• If a user chooses the line tool in Adobe Photoshop, she is in a different mode than she was before when she worked with the paintbrush tool; in this case, a mode resembles the real-life choice of physical drawing tools (13)
• A dialog box displaying an error may disable the user to go further with her work in that application in order to draw her attention to the problem.

Users have to be given a clue to the mode they find themselves in, for example by changing the look of a pointer.

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