Bug 164529 [FieldAssist] Provide the ability to listen to start and end field assist events
In the previous content assist functionality, an ICompletionListener could be specified to listen to the following events: public void assistSessionEnded(ContentAssistEvent event) public void assistSessionStarted(ContentAssistEvent event) The equivalent listener, IContentProposalListener, does not listen to those two events. PDE needs to know when an assist session is ended in order to reset the state it maintains for custom filtering of java type results. The current event does not handle the case where the user ends the content assist without selecting a proposal: public void proposalAccepted(IContentProposal proposal);
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
private Table proposalTable;
		/*
		 * The proposals to be shown (cached to avoid repeated requests).
		 */
		private IContentProposal[] proposals;
		/*
		 * Secondary popup used to show detailed information about the selected
		 * proposal..
		 */
		private InfoPopupDialog infoPopup;
		/*
		 * Flag indicating whether there is a pending secondary popup update.
		 */
		private boolean pendingDescriptionUpdate = false;
		/*
		 * Filter text - tracked while popup is open, only if we are told to
		 * filter
		 */
		private String filterText = EMPTY;
		/**
		 * Constructs a new instance of this popup, specifying the control for
		 * which this popup is showing content, and how the proposals should be
		 * obtained and displayed.
		 * 
		 * @param infoText
		 *            Text to be shown in a lower info area, or
		 *            <code>null</code> if there is no info area.
		 */
		ContentProposalPopup(String infoText, IContentProposal[] proposals) {