Bug 147377 [Field Assist] - open proposal popup should close when there are no valid proposals left
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
boolean hasFocus() {
				if (text == null || text.isDisposed()) {
					return false;
				}
				return text.getShell().isFocusControl()
						|| text.isFocusControl();
			}
		}
		/*
		 * The listener installed on the target control.
		 */
		private Listener targetControlListener;
		/*
		 * The listener installed in order to close the popup.
		 */
		private PopupCloserListener popupCloser;
		/*
		 * The table used to show the list of proposals.
		 */
		private Table proposalTable;
		/*
		 * The proposals to be shown (cached to avoid repeated requests).
		 */
		private IContentProposal[] proposals;
		/*
		 * Secondary popup used to show detailed information about the selected
		 * proposal..
		 */
		private InfoPopupDialog infoPopup;
		/*