Bug 125955 [Field Assist] - StringIndexOutOfBoundsException when backspacing out of a filter
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
/**
		 * Closes this popup. This method is extended to remove the control
		 * listener.
		 * 
		 * @return <code>true</code> if the window is (or was already) closed,
		 *         and <code>false</code> if it is still open
		 */
		public boolean close() {
			removeControlListener();
			return super.close();
		}
		/*
		 * Get the proposals from the proposal provider. The provider may or may
		 * not filter the proposals based on the specified filter text.
		 */
		private IContentProposal[] getProposals(String filterString) {
			if (proposalProvider == null)
				return null;
			int position = getControlContentAdapter().getCursorPosition(
					getControl());
			String contents = getControlContentAdapter().getControlContents(
					getControl());
			IContentProposal[] proposals = proposalProvider.getProposals(
					contents, position);
			if (filter) {
				return filterProposals(proposals, filterString);
			}
			return proposals;
		}
		/*