Bug 54347 [Dialogs] Provide "Yes No Always Never" dialog
In Debug UI, we define a dialog that prompts the user to answer Yes, No, Always, or Never. If anyone's interested, this code is generic and could be shipped as a JFace component. The dialog is in the org.eclipse.debug.ui project; the type name is AlwaysNeverDialog. The dialog supports passing in a preference store and preference key for the dialog to persist an Always or Never selection. For cases where clients don't have a preference store but still want to be able to get at the user's response, it alternatively supports passing in a string buffer where the dialog will store the "always/never/prompt" status.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/IDEWorkbenchAdvisor.java
* The dialog setting key to access the known installed features
	 * since the last time the workbench was run.
	 */
	private static final String INSTALLED_FEATURES = "installedFeatures"; 
	
	private static IDEWorkbenchAdvisor workbenchAdvisor = null;
	/**
	 * Event loop exception handler for the advisor.
	 */
	private IDEExceptionHandler exceptionHandler = null;
	
	/**
	 * Contains the workspace location if the -showlocation command line
	 * argument is specified, or <code>null</code> if not specified.
	 */
	private String workspaceLocation = null;
	/**
	 * Ordered set of versioned feature ids new for this session; <code>null</code>
	 * if uninitialized. Element type: <code>String</code>
	 */
	private Set newlyAddedFeatures = null;
	
	/**
	 * List of <code>AboutInfo</code> for all new installed
	 * features that specify a welcome perspective.
	 */
	private ArrayList welcomePerspectiveInfos = null;
	
	/**
	 * Helper for managing activites in response to workspace changes.