Bug 49117 [Plan Item] Workbench needs hooks for new welcome support
M6 We need to provide an extension point and some interfaces to allow for a primary feature to declare a welcome page. This extension point will be tied the new IProduct being defined by the Core team and needs to have 3 states 1) Fill whole screen 2) Collapsed on the right when the user selects something and starts working 3) Disables when it is no longer of any use
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/IDEWorkbenchPlugin.java
public static final String PL_CAPABILITIES = "capabilities"; 
	public static final String PL_PROJECT_NATURE_IMAGES ="projectNatureImages"; 
	
	/**
	 * Project image registry; lazily initialized.
	 */	
	private ProjectImageRegistry projectImageRegistry = null;
	/**
	 * Marker image registry; lazily initialized.
	 */	
	private MarkerImageProviderRegistry markerImageProviderRegistry = null;
	/**
	 * Capability registry; lazily initialized.
	 */	
	private CapabilityRegistry capabilityRegistry;
	/**
	 * List of about info for all know features; lazily initialized.
	 */
	private AboutInfo[] cachedAboutInfos = null;
	
	/**
	 * Create an instance of the IDEWorkbenchPlugin.
	 * The workbench plugin is effectively the "application" for the workbench UI.
	 * The entire UI operates as a good plugin citizen.
	 */
	public IDEWorkbenchPlugin(IPluginDescriptor descriptor) {
		super(descriptor);
		inst = this;
	}