Bug 144522 [Field Assist] - should proposal popup ever open if empty?
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
/*
	 * A boolean that indicates whether key events received while the proposal
	 * popup is open should also be propagated to the control. Default value is
	 * true.
	 */
	private boolean propagateKeys = true;
	/*
	 * Integer that indicates the filtering style. One of FILTER_CHARACTER,
	 * FILTER_CUMULATIVE, FILTER_NONE.
	 */
	private int filterStyle = FILTER_NONE;
	/*
	 * The listener we install on the control.
	 */
	private Listener controlListener;
	/*
	 * The list of listeners who wish to be notified when something significant
	 * happens with the proposals.
	 */
	private ListenerList proposalListeners = new ListenerList();
	/*
	 * Flag that indicates whether the adapter is enabled. In some cases,
	 * adapters may be installed but depend upon outside state.
	 */
	private boolean isEnabled = true;
	/*
	 * The delay in milliseconds used when autoactivating the popup.
	 */
	private int autoActivationDelay = 0;