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
* 
	 * @param event the property change event
	 */
	protected void handlePreferencePropertyChanged(org.eclipse.core.runtime.Preferences.PropertyChangeEvent event) {
		if (COMPILER_TASK_TAGS.equals(event.getProperty())) {
			ISourceViewer sourceViewer= getSourceViewer();
			if (sourceViewer != null && affectsTextPresentation(new PropertyChangeEvent(event.getSource(), event.getProperty(), event.getOldValue(), event.getNewValue())))
				sourceViewer.invalidateTextPresentation();
		}
	}
	/**
	 * Returns a segmentation of the line of the given viewer's input document appropriate for
	 * bidi rendering. The default implementation returns only the string literals of a java code
	 * line as segments.
	 * 
	 * @param viewer the text viewer
	 * @param lineOffset the offset of the line
	 * @return the line's bidi segmentation
	 * @throws BadLocationException in case lineOffset is not valid in document
	 */
	public static int[] getBidiLineSegments(ITextViewer viewer, int lineOffset) throws BadLocationException {
			
		IDocument document= viewer.getDocument();
		if (document == null)
			return null;
			
		IRegion line= document.getLineInformationOfOffset(lineOffset);
		ITypedRegion[] linePartitioning= TextUtilities.computePartitioning(document, IJavaPartitions.JAVA_PARTITIONING, lineOffset, line.getLength());
		
		List segmentation= new ArrayList();