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
*/
			private String contents = EMPTY;
			/*
			 * Construct an info-popup with the specified parent.
			 */
			InfoPopupDialog(Shell parent) {
				super(parent, PopupDialog.HOVER_SHELLSTYLE, false, false,
						false, false, null, null);
			}
			/*
			 * Create a text control for showing the info about a proposal.
			 */
			protected Control createDialogArea(Composite parent) {
				text = new Text(parent, SWT.MULTI | SWT.READ_ONLY | SWT.WRAP
						| SWT.NO_FOCUS);
				
				GridData gd = new GridData(GridData.BEGINNING
						| GridData.FILL_BOTH);
				gd.horizontalIndent = PopupDialog.POPUP_HORIZONTALSPACING;
				gd.verticalIndent = PopupDialog.POPUP_VERTICALSPACING;
				text.setLayoutData(gd);
				text.setText(contents);
				
				text.addFocusListener(new FocusAdapter() {
					public void focusGained(FocusEvent event) {
						ContentProposalPopup.this.close();
					}
				});
				return text;
			}