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
fImageDescriptorRegistry.dispose();
		
		unregisterAdapters();
		
		super.shutdown();
		
		if (fWorkingCopyManager != null) {
			fWorkingCopyManager.shutdown();
			fWorkingCopyManager= null;
		}
		
		if (fCompilationUnitDocumentProvider != null) {
			fCompilationUnitDocumentProvider.shutdown();
			fCompilationUnitDocumentProvider= null;
		}
				
		if (fJavaTextTools != null) {
			fJavaTextTools.dispose();
			fJavaTextTools= null;
		}
		
		JavaDocLocations.shutdownJavadocLocations();
		
		JFaceResources.getFontRegistry().removeListener(fFontPropertyChangeListener);
	}
		
	private IWorkbenchPage internalGetActivePage() {
		IWorkbenchWindow window= getWorkbench().getActiveWorkbenchWindow();
		if (window == null)
			return null;