if (fListener == null) { fListener= this; JavaCore.addElementChangedListener(fListener); }
	public void add(IWorkingSet workingSet) {		synchronized (fWorkingSets) {			checkElementExistence(workingSet);			fWorkingSets.add(workingSet);		}		if (fListener == null) {			fListener= this;			JavaCore.addElementChangedListener(fListener);		}	}