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
} finally {
				fDocument.removeDocumentListener(this);
			}
			return Status.OK_STATUS;
		}
		/*
		 * @see org.eclipse.jface.text.IDocumentListener#documentAboutToBeChanged(org.eclipse.jface.text.DocumentEvent)
		 */
		public void documentAboutToBeChanged(DocumentEvent event) {
			fCancelled= true;
		}
		/*
		 * @see org.eclipse.jface.text.IDocumentListener#documentChanged(org.eclipse.jface.text.DocumentEvent)
		 */
		public void documentChanged(DocumentEvent event) {
		}
	}	
	
	/**
	 * Updates the occurrences annotations based
	 * on the current selection.
	 *
	 * @since 3.0
	 */
	protected void updateOccurrenceAnnotations(ITextSelection selection, CompilationUnit astRoot) {
		if (!fMarkOccurrenceAnnotations)
			return;
		
		if (astRoot == null || selection == null)
			return;