Bug 250604 [FieldAssist] API - ContentProposalAdapter needs isShowing() method
Please implement a method ContentProposalAdapter.isShwoing(). The method should return a boolean whether the content assistant proposal popup is open or not.
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
* proposal..
		 */
		private InfoPopupDialog infoPopup;
		/*
		 * Flag indicating whether there is a pending secondary popup update.
		 */
		private boolean pendingDescriptionUpdate = false;
		/*
		 * Filter text - tracked while popup is open, only if we are told to
		 * filter
		 */
		private String filterText = EMPTY;
		/**
		 * Constructs a new instance of this popup, specifying the control for
		 * which this popup is showing content, and how the proposals should be
		 * obtained and displayed.
		 * 
		 * @param infoText
		 *            Text to be shown in a lower info area, or
		 *            <code>null</code> if there is no info area.
		 */
		ContentProposalPopup(String infoText, IContentProposal[] proposals) {
			
			
			
			
			
			
			
			super(control.getShell(), SWT.RESIZE | SWT.ON_TOP, false, false, false,