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/CompilationUnitDocumentProvider.java
*/
	protected ICompilationUnit createCompilationUnit(IFile file) {
		Object element= JavaCore.create(file);
		if (element instanceof ICompilationUnit)
			return (ICompilationUnit) element;
		return null;
	}
	/*
	 * @see org.eclipse.ui.editors.text.TextFileDocumentProvider#createEmptyFileInfo()
	 */
	protected FileInfo createEmptyFileInfo() {
		return new CompilationUnitInfo();
	}
	/*
	 * @see org.eclipse.ui.editors.text.TextFileDocumentProvider#createAnnotationModel(org.eclipse.core.resources.IFile)
	 */
	protected IAnnotationModel createAnnotationModel(IFile file) {
		return new CompilationUnitAnnotationModel(file);
	}
	/*
	 * @see org.eclipse.ui.editors.text.TextFileDocumentProvider#createFileInfo(java.lang.Object)
	 */
	protected FileInfo createFileInfo(Object element) throws CoreException {
		ICompilationUnit original= null;
		if (element instanceof IFileEditorInput) {
			IFileEditorInput input= (IFileEditorInput) element;
			original= createCompilationUnit(input.getFile());
			if (original == null)
				return null;
		}