Bug 148357 [Field Assist] - API - provide access for closing the proposal popup
I think that the field assist API needs more hooks to be customizable. For example : 1) There is no way to manually close/open the popup. Most of the times, this is the easier thing for a user to ask to implement his custom behaviour. 2) There is no way to intercept keystrokes/events directed to the field. 3) There is no way to control focus.
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
*/
	public static final int PROPOSAL_IGNORE = 3;
	/**
	 * Indicates that there should be no filter applied as keys are typed in the
	 * popup.
	 */
	public static final int FILTER_NONE = 1;
	/**
	 * Indicates that a single character filter applies as keys are typed in the
	 * popup.
	 */
	public static final int FILTER_CHARACTER = 2;
	/**
	 * Indicates that a cumulative filter applies as keys are typed in the
	 * popup. That is, each character typed will be added to the filter.
	 */
	public static final int FILTER_CUMULATIVE = 3;
	/*
	 * Set to <code>true</code> to use a Table with SWT.VIRTUAL. This is a
	 * workaround for https://bugs.eclipse.org/bugs/show_bug.cgi?id=98585#c40
	 * The corresponding SWT bug is
	 * https://bugs.eclipse.org/bugs/show_bug.cgi?id=90321
	 */
	private static final boolean USE_VIRTUAL = !"motif".equals(SWT.getPlatform()); 
	/*
	 * The delay before showing a secondary popup.
	 */
	private static final int POPUP_DELAY = 750;
	/*
	 * The character height hint for the popup. May be overridden by using