Bug 120168 [Field Assist] - should be able to specify character activation subset when auto-activating
ControlContentAdapter (initial release) When there is no triggering keystroke set on a ControlContentAdapter, auto-activation is assumed, and alpha-numerics trigger the auto-activation. It is useful to be able to specify a subset of characters that trigger auto-activation. This is done, for example, by the find/replace dialog RexExProcessor, so that only those characters involving regular expressions will auto-activate the content assist.
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
*            content proposals for this control, or <code>null</code> if
	 *            no content proposal is available.
	 * @param labelProvider
	 *            the label provider which provides text and image information
	 *            for content proposals. A <code>null</code> value indicates
	 *            that a default label provider is sufficient for any content
	 *            proposals that may occur.
	 * @param keyStroke
	 *            the keystroke that will invoke the content proposal popup. If
	 *            this value is <code>null</code>, then proposals will be
	 *            shown as soon as any valid content key is typed (type-ahead
	 *            mode).
	 * @param propagateKeyStroke
	 *            a boolean that indicates whether the triggering keystroke
	 *            should be propagated to the adapted control, as well as
	 *            subsequent keystrokes typed into the control.
	 * @param acceptance
	 *            a constant indicating how an accepted proposal should affect
	 *            the control's content. Should be one of
	 *            <code>PROPOSAL_INSERT</code>, <code>PROPOSAL_REPLACE</code>,
	 *            or <code>PROPOSAL_IGNORE</code>
	 * 
	 */
	public ContentProposalAdapter(Control control,
			IControlContentAdapter controlContentAdapter,
			IContentProposalProvider proposalProvider,
			ILabelProvider labelProvider, KeyStroke keyStroke,
			boolean propagateKeyStroke, int acceptance) {
		super();
		this.control = control;