Bug 115711 [content assist] Parameter hints disappear immediately
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/text/java/ExperimentalProposal.java
private IRegion fSelectedRegion; 
	private int[] fArgumentOffsets;
	private int[] fArgumentLengths;
	public ExperimentalProposal(CompletionProposal proposal, CompletionContext context, ICompilationUnit cu, CompletionProposalLabelProvider labelProvider) {
		super(proposal, context, cu, labelProvider);
	}
	/*
	 * @see ICompletionProposalExtension#apply(IDocument, char)
	 */
	public void apply(IDocument document, char trigger, int offset) {
		super.apply(document, trigger, offset);
		int baseOffset= getReplacementOffset();
		String replacement= getReplacementString();
		if (fArgumentOffsets != null && getTextViewer() != null) {
			try {
				LinkedModeModel model= new LinkedModeModel();
				for (int i= 0; i != fArgumentOffsets.length; i++) {
					LinkedPositionGroup group= new LinkedPositionGroup();
					group.addPosition(new LinkedPosition(document, baseOffset + fArgumentOffsets[i], fArgumentLengths[i], LinkedPositionGroup.NO_STOP));
					model.addGroup(group);
				}
				model.forceInstall();
				JavaEditor editor= getJavaEditor();
				if (editor != null) {
					model.addLinkingListener(new EditorHighlightingSynchronizer(editor));
				}