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
* narrowing and navigating the list of proposals provided once the popup is
	 * open. Filtering of the proposals will occur even when the control content
	 * is not affected by user typing. Note that automatic filtering is not used
	 * to achieve content-sensitive filtering such as auto-completion. Filtering
	 * that is sensitive to changes in the control content should be performed
	 * by the supplied {@link IContentProposalProvider}.
	 * 
	 * @param filterStyle
	 *            a constant indicating how keystrokes received in the proposal
	 *            popup affect filtering of the proposals shown.
	 *            <code>FILTER_NONE</code> specifies that no automatic
	 *            filtering of the content proposal list will occur as keys are
	 *            typed in the popup. <code>FILTER_CUMULATIVE</code> specifies
	 *            that the content of the popup will be filtered by a string
	 *            containing all the characters typed since the popup has been
	 *            open. <code>FILTER_CHARACTER</code> specifies that the
	 *            content of the popup will be filtered by the most recently
	 *            typed character.
	 */
	public void setFilterStyle(int filterStyle) {
		this.filterStyle = filterStyle;
	}
	/**
	 * Return the size, in pixels, of the content proposal popup.
	 * 
	 * @return a Point specifying the last width and height, in pixels, of the
	 *         content proposal popup.
	 */
	public Point getPopupSize() {
		return popupSize;