Bug 96917 [implementation] If two editors use the 2.x-compatible API, one or both doesn't work
At least one problem is that 3.0 installs partitioners for every editor that might possibly edit a file, but each editor expects its own partitioner to be installed. Leading to the famous white screen with blue line.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/ClassFileDocumentProvider.java
ClassFileMarkerAnnotationModel model= new ClassFileMarkerAnnotationModel(resource);
			model.setClassFile(classFile);
			return model;
		}
		return null;
	}
	/*
	 * @see org.eclipse.ui.editors.text.StorageDocumentProvider#createEmptyDocument()
	 * @since 3.1
	 */
	protected IDocument createEmptyDocument() {
		return new PartiallySynchronizedDocument();
	}
	/*
	 * @see AbstractDocumentProvider#createDocument(Object)
	 */
	protected IDocument createDocument(Object element) throws CoreException {
		IDocument document= super.createDocument(element);
		if (document != null) {
			JavaTextTools tools= JavaPlugin.getDefault().getJavaTextTools();
			tools.setupJavaDocumentPartitioner(document, IJavaPartitions.JAVA_PARTITIONING);
		}
		return document;
	}
	/*
	 * @see AbstractDocumentProvider#createElementInfo(Object)
	 */
	protected ElementInfo createElementInfo(Object element) throws CoreException {
		if (element instanceof IClassFileEditorInput) {
			IClassFileEditorInput input = (IClassFileEditorInput) element;