Bug 115711 [content assist] Parameter hints disappear immediately
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/text/java/ParameterGuessingProposal.java
protected boolean needsLinkedMode() {
		return false; 
	}
	
	/*
	 * @see org.eclipse.jdt.internal.ui.text.java.JavaMethodCompletionProposal#computeReplacementString()
	 */
	protected String computeReplacementString() {
		
		if (!hasParameters() || !hasArgumentList())
			return super.computeReplacementString();
		
		long millis= DEBUG ? System.currentTimeMillis() : 0;
		String replacement;
		try {
			replacement= computeGuessingCompletion();
		} catch (JavaModelException x) {
			fPositions= null;
			fChoices= null;
			JavaPlugin.log(x);
			openErrorDialog(x);
			return super.computeReplacementString();
		}
		if (DEBUG) System.err.println("Parameter Guessing: " + (System.currentTimeMillis() - millis));  
		
		return replacement;
	}
	/**
	 * Creates the completion string. Offsets and Lengths are set to the offsets and lengths
	 * of the parameters.