Bug 125955 [Field Assist] - StringIndexOutOfBoundsException when backspacing out of a filter
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
public void addContentProposalListener(IContentProposalListener listener) {
		proposalListeners.add(listener);
	}
	/*
	 * Add our listener to the control. Debug information to be left in until
	 * this support is stable on all platforms.
	 */
	private void addControlListener(Control control) {
		if (DEBUG)
			System.out
					.println("ContentProposalListener#installControlListener()"); 
		if (controlListener != null)
			return;
		controlListener = new Listener() {
			public void handleEvent(Event e) {
				if (!isEnabled)
					return;
				switch (e.type) {
				case SWT.KeyDown:
					if (DEBUG)
						dump("keyDown OK", e); 
					if (triggerKeyStroke != null) {
						
						
						if ((triggerKeyStroke.getModifierKeys() == KeyStroke.NO_KEY && triggerKeyStroke
								.getNaturalKey() == e.character)
								||
								
								
								(triggerKeyStroke.getNaturalKey() == e.keyCode && ((triggerKeyStroke