Bug 52801 "Press F2 for focus" does not work for spell-checking hovers
"Press F2 for focus" does not work for spell-checking hovers.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/JavaEditor.java
protected void uninstallOccurrencesFinder() {
		fMarkOccurrenceAnnotations= false;
		
		if (fOccurrencesFinderJob != null) {
			fOccurrencesFinderJob.cancel();
			fOccurrencesFinderJob= null;
		}
		
		if (fPostSelectionListenerWithAST != null) {
			SelectionListenerWithASTManager.getDefault().removeListener(this, fPostSelectionListenerWithAST);
			fPostSelectionListenerWithAST= null;
		}
		
		removeOccurrenceAnnotations();
	}	
	
	void removeOccurrenceAnnotations() {
		IDocumentProvider documentProvider= getDocumentProvider();
		if (documentProvider == null)
			return;
		
		IAnnotationModel annotationModel= documentProvider.getAnnotationModel(getEditorInput());
		if (annotationModel == null || fOccurrenceAnnotations == null)
			return;
		synchronized (annotationModel) {
			if (annotationModel instanceof IAnnotationModelExtension) {
				((IAnnotationModelExtension)annotationModel).replaceAnnotations(fOccurrenceAnnotations, null);
			} else {
				for (int i= 0, length= fOccurrenceAnnotations.length; i < length; i++)
					annotationModel.removeAnnotation(fOccurrenceAnnotations[i]);