Bug 40788 [plan item] Configurable Next/Previous actions
Toolbar drop down, or editor specific control. Needs to be coordinated with Platform UI.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/JavaPlugin.java
private synchronized ImageDescriptorRegistry internalGetImageDescriptorRegistry() {
		if (fImageDescriptorRegistry == null)
			fImageDescriptorRegistry= new ImageDescriptorRegistry();
		return fImageDescriptorRegistry;
	}
	private void registerAdapters() {
		fJavaElementAdapterFactory= new JavaElementAdapterFactory();
		fMarkerAdapterFactory= new MarkerAdapterFactory();
		fEditorInputAdapterFactory= new EditorInputAdapterFactory();
		fResourceAdapterFactory= new ResourceAdapterFactory();
		fLogicalPackageAdapterFactory= new LogicalPackageAdapterFactory();
		IAdapterManager manager= Platform.getAdapterManager();		
		manager.registerAdapters(fJavaElementAdapterFactory, IJavaElement.class);
		manager.registerAdapters(fMarkerAdapterFactory, IMarker.class);
		manager.registerAdapters(fEditorInputAdapterFactory, IEditorInput.class);
		manager.registerAdapters(fResourceAdapterFactory, IResource.class);
		manager.registerAdapters(fLogicalPackageAdapterFactory, LogicalPackage.class);
	}
	
	private void unregisterAdapters() {
		IAdapterManager manager= Platform.getAdapterManager();
		manager.unregisterAdapters(fJavaElementAdapterFactory);
		manager.unregisterAdapters(fMarkerAdapterFactory);
		manager.unregisterAdapters(fEditorInputAdapterFactory);
		manager.unregisterAdapters(fResourceAdapterFactory);
		manager.unregisterAdapters(fLogicalPackageAdapterFactory);
	}
}