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/filebuffers/CompilationUnitDocumentProvider2.java
CompilationUnitAnnotationModel model= (CompilationUnitAnnotationModel) cuInfo.fModel;
			model.setCompilationUnit(cuInfo.fCopy);
		}
		cuInfo.fModel.addAnnotationModelListener(fGlobalAnnotationModelListener);
						
		if (requestor instanceof IProblemRequestorExtension) {
			IProblemRequestorExtension extension= (IProblemRequestorExtension) requestor;
			extension.setIsActive(isHandlingTemporaryProblems());
		}
		
		return cuInfo;
	}
	
	/*
	 * @see org.eclipse.ui.editors.text.TextFileDocumentProvider#disposeFileInfo(java.lang.Object, org.eclipse.ui.editors.text.TextFileDocumentProvider.FileInfo)
	 */
	protected void disposeFileInfo(Object element, FileInfo info) {
		if (info instanceof CompilationUnitInfo) {
			CompilationUnitInfo cuInfo= (CompilationUnitInfo) info;
			
			if (JavaPlugin.USE_WORKING_COPY_OWNERS)  {
				
				try  {
					cuInfo.fCopy.discardWorkingCopy();
				} catch (JavaModelException x)  {
					handleCoreException(x, x.getMessage());
				}
			
			} else  {
				cuInfo.fCopy.destroy();