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5	Panels

Panels support the work done in the principal windows of an application.  Like menus, most panels are vehicles through which the user can give instructions to the application.  But unlike menus, they aren't restricted to a single column of commands:  A panel can provide the user with a variety of different control objectsÐbuttons, sliders, text fields, and moreÐarranged as best suits its purpose.  The Font, Find, Page Layout, and Open panels are all examples.  Such panels can be viewed as generalized and more versatile menus.

Some panels play a different role, however.  Instead of letting the user give instructions to the application, they give information to the user.  Help panels, the Info panel, and attention panels that display warnings are examples.

What unites all panelsÐwhether they convey instructions from the user to the application or information from the application to the userÐis that they play conventional, supporting roles.  Unlike windows, none of them is a site for the user's main work in the application.  In a panel, the dialog between the application and the user is highly structured in both form and content.

This chapter first describes the basic attributes of ordinary panels, and then describes how attention panels are different.  The last section gives guidelines on creating your own panels and using the ones supplied by the Application Kit.