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
/**
	 * Indicates that there should be no filter applied as keys are typed in the
	 * popup.
	 */
	public static final int FILTER_NONE = 1;
	/**
	 * Indicates that a single character filter applies as keys are typed in the
	 * popup.
	 */
	public static final int FILTER_CHARACTER = 2;
	/**
	 * Indicates that a cumulative filter applies as keys are typed in the
	 * popup. That is, each character typed will be added to the filter.
	 * 
	 * @deprecated As of 3.4, filtering that is sensitive to changes in the
	 *             control content should be performed by the supplied
	 *             {@link IContentProposalProvider}, such as that performed by
	 *             {@link SimpleContentProposalProvider}
	 */
	public static final int FILTER_CUMULATIVE = 3;
	/*
	 * Set to <code>true</code> to use a Table with SWT.VIRTUAL. This is a
	 * workaround for https://bugs.eclipse.org/bugs/show_bug.cgi?id=98585#c40
	 * The corresponding SWT bug is
	 * https://bugs.eclipse.org/bugs/show_bug.cgi?id=90321
	 */
	private static final boolean USE_VIRTUAL = !Util.isMotif();
	/*
	 * The delay before showing a secondary popup.
	 */