Bug 144522 [Field Assist] - should proposal popup ever open if empty?
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
Runnable runnable = new Runnable() {
					public void run() {
						pendingDescriptionUpdate = true;
						try {
							Thread.sleep(POPUP_DELAY);
						} catch (InterruptedException e) {
						}
						if (!isValid()) {
							return;
						}
						getShell().getDisplay().syncExec(new Runnable() {
							public void run() {
								
								
								IContentProposal p = getSelectedProposal();
								if (p != null) {
									if (infoPopup == null) {
										infoPopup = new InfoPopupDialog(
												getShell());
										infoPopup.open();
										infoPopup.getShell()
												.addDisposeListener(
														new DisposeListener() {
															public void widgetDisposed(
																	DisposeEvent event) {
																infoPopup = null;
															}
														});
									}