Bug 132039 [Field Assist] - secondary popup should update on same delay as its invocation delay
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
private boolean isValid() {
			return proposalTable != null && !proposalTable.isDisposed();
		}
		/*
		 * Return whether the receiver has focus.
		 */
		private boolean hasFocus() {
			if (!isValid()) {
				return false;
			}
			return getShell().isFocusControl()
					|| proposalTable.isFocusControl();
		}
		/*
		 * Return the current selected proposal.
		 */
		private IContentProposal getSelectedProposal() {
			if (isValid()) {
				int i = proposalTable.getSelectionIndex();
				if (proposals == null || i < 0 || i >= proposals.length) {
					return null;
				}
				return proposals[i];
			}
			return null;
		}
		/*
		 * Select the proposal at the given index.
		 */
		private void selectProposal(int index) {