Also in contrast to VkPrefGroup, VkPrefList does not display any label for the group.Д®ach preference item maintains its own state or value, and your program can query the value of preference items as needed. Unlike VkPrefGroup, items are not padded so that they take equal space instead, each item takes only as much space as it needs.

The VkPrefList class arranges its items vertically. You have the option of displaying a label for the group.Дefines a group of related items. Items are always padded so that they take equal space. You can specify either vertical or horizontal layout the default is vertical. You have the option of displaying a label for the group.ДЄ subclass of VkPrefGroup for managing a group of toggle items in a radio box style. With a vertical layout, VkPrefGroup pads items so that they take equal space. The preference dialog activates this callback whenever the user clicks the dialog's Apply, OK, or Cancel button.Дefines a group of related items. The VkPrefDialog class also supplies a ViewKit callback named prefCallback. Users can also click the Cancel button to return all preferences to their last applied values and dismiss the dialog.

Users can change the values associated with any number of preference items, then click the Apply button to apply all changes and keep the dialog up, or the OK button to apply all changes and dismiss the dialog. Each preference item maintains its own state or value, and your program can query the value of preference items as needed. For very simple preference dialogs (for example, just a few toggle buttons), you might be able to directly instantiate a VkPrefDialog object however, in most cases you should create a separate subclass of VkPrefDialog for each preference dialog in your application.ДЇor each preference dialog, you create a collection of preference items and associate them with the dialog. Instead, you must create a separate instance of VkPrefDialog for each preference dialog that you want to display in your program. Therefore, unlike the other dialog classes, VkPrefDialog does not create a global instance of a preference dialog. On the other hand, individual postings of preference dialogs often vary significantly they usually have greatly different preference items and data structures associated with each preference item. Details such the message, the button labels, or the dialog title change from posting to posting, but the general dialog behavior remains the same. For the other dialog classes, a single, reusable instance of each type of dialog is sufficient. However, there are some significant differences in the way you use preference dialogs in your programs compared to the other dialog classes. Thus, the VkPrefDialog class inherits all of the functions and data members provided by these base classes. Specifically, the base preference dialog class, VkPrefDialog, is a subclass of VkGenericDialog, which is in turn a subclass of VkDialogManager. In ViewKit, preference dialogs are implemented as a specialized class of dialog.

Layout is handled automatically, and ViewKit provides the ability to apply or revert all preferences to their previous state. These items maintain their own states, which allows an application to simply query each item to see if it has been changed. Rather than dealing directly with widgets, their placement, callbacks, and so on, programmers who use ViewKit can simply create groups of preference items. ViewKit supports an easy-to-use collection of classes for building preference dialogs. A user also expects to be able to click Cancel and return all preferences to their previous state, regardless of how many changes the user might have made. Usually, a user sets a number of preferences and then clicks an Apply button or an OK button to apply all changes at once. A user expects preference dialogs to work in a specific way, as well. Without high-level support, preference dialogs can take considerable time and effort to write because they can involve large numbers of text input fields, labels, toggle buttons, and other controls. Preference dialogs allow users to customize the behavior of an application.

Viewkit sgi tutorial