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
if (autoActivationCharacters == null) {
			this.autoActivateString = null;
		} else {
			this.autoActivateString = new String(autoActivationCharacters);
		}
	}
	/**
	 * Set the delay, in milliseconds, used before any autoactivation is
	 * triggered.
	 * 
	 * @return the time in milliseconds that will pass before a popup is
	 *         automatically opened
	 */
	public int getAutoActivationDelay() {
		return autoActivationDelay;
	}
	/**
	 * Set the delay, in milliseconds, used before autoactivation is triggered.
	 * 
	 * @param delay
	 *            the time in milliseconds that will pass before a popup is
	 *            automatically opened
	 */
	public void setAutoActivationDelay(int delay) {
		autoActivationDelay = delay;
	}
	/**
	 * Get the integer style that indicates how an accepted proposal affects the
	 * control's content.
	 *