Bug 40785 [plan item] Overview ruler improvements
- navigation from ruler to editor - hovering over header area shows number of errors/warning (header annotations in general)
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/CompilationUnitDocumentProvider.java
fGlobalAnnotationModelListener.addListener(listener);
	}
	/*
	 * @see org.eclipse.jdt.internal.ui.javaeditor.ICompilationUnitDocumentProvider#removeGlobalAnnotationModelListener(org.eclipse.jface.text.source.IAnnotationModelListener)
	 */
	public void removeGlobalAnnotationModelListener(IAnnotationModelListener listener) {
		fGlobalAnnotationModelListener.removeListener(listener);
	}
	/*
	 * @see org.eclipse.jdt.internal.ui.javaeditor.ICompilationUnitDocumentProvider#getWorkingCopy(java.lang.Object)
	 */
	public ICompilationUnit getWorkingCopy(Object element) {
		
		ElementInfo elementInfo= getElementInfo(element);		
		if (elementInfo instanceof CompilationUnitInfo) {
			CompilationUnitInfo info= (CompilationUnitInfo) elementInfo;
			return info.fCopy;
		}
		
		return null;
	}
	/*
	 * @see org.eclipse.ui.texteditor.IDocumentProviderExtension3#createEmptyDocument(java.lang.Object)
	 */
	public IDocument createEmptyDocument(Object element) {
		return createEmptyDocument();
	}
	
	/*
	 * @see org.eclipse.ui.editors.text.StorageDocumentProvider#setupDocument(java.lang.Object, org.eclipse.jface.text.IDocument)