Bug 125955 [Field Assist] - StringIndexOutOfBoundsException when backspacing out of a filter
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
return EMPTY;
			if (labelProvider == null)
				return proposal.getLabel() == null ? proposal.getContent()
						: proposal.getLabel();
			return labelProvider.getText(proposal);
		}
		/*
		 * Get the image for the specified proposal. If there is no image
		 * available, return null.
		 */
		private Image getImage(IContentProposal proposal) {
			if (proposal == null || labelProvider == null)
				return null;
			return labelProvider.getImage(proposal);
		}
		/*
		 * Return an empty array. Used so that something always shows in the
		 * proposal popup, even if no proposal provider was specified.
		 */
		private IContentProposal[] getEmptyProposalArray() {
			return new IContentProposal[0];
		}
		/*
		 * Add a listener to the target control. We monitor key and traverse
		 * events in the target control while we are open, in order to handle
		 * traversal and navigation requests.
		 */
		private void addControlListener() {
			targetControlListener = new TargetControlListener();
			control.addListener(SWT.KeyDown, targetControlListener);