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
return getWorkbench().getActiveWorkbenchWindow().getActivePage();
	}
		
	public synchronized CompilationUnitDocumentProvider getCompilationUnitDocumentProvider() {
		if (fCompilationUnitDocumentProvider == null)
			fCompilationUnitDocumentProvider= new CompilationUnitDocumentProvider();
		return fCompilationUnitDocumentProvider;
	}
	
	public synchronized ClassFileDocumentProvider getClassFileDocumentProvider() {
		if (fClassFileDocumentProvider == null)
			fClassFileDocumentProvider= new ClassFileDocumentProvider();
		return fClassFileDocumentProvider;
	}
	public synchronized IWorkingCopyManager getWorkingCopyManager() {
		if (fWorkingCopyManager == null) {
			CompilationUnitDocumentProvider provider= getCompilationUnitDocumentProvider();
			fWorkingCopyManager= new WorkingCopyManager(provider);
		}
		return fWorkingCopyManager;
	}
	
	public synchronized ProblemMarkerManager getProblemMarkerManager() {
		if (fProblemMarkerManager == null)
			fProblemMarkerManager= new ProblemMarkerManager();
		return fProblemMarkerManager;
	}	
	
	public synchronized JavaTextTools getJavaTextTools() {
		if (fJavaTextTools == null)