Bug 156456 [Forms] widgets accept focus even though they can't do anything with it
Many of the widgets in the Forms library (Section, BusyIndicator, FormHeading) will accept keyboard focus even though they can't do anything with it. The impact is that when someone calls setFocus on a Form that contains a FormHeading at its top (which is quite common), keyboard focus ends up nowhere. Looking at the patterns in SWT, it appears that the correct protocol is for controls to return false from setFocus if they can't do anything with the focus so that the caller can try assigning focus somewhere else.
bundles/org.eclipse.ui.forms/src/org/eclipse/ui/forms/widgets/ExpandableComposite.java
*/
	protected ToggleHyperlink toggle;
	/**
	 * The text label for the title.
	 */
	protected Control textLabel;
	/**
	 * @deprecated this variable was left as protected by mistake. It will be
	 *             turned into static and hidden in the future versions. Do not
	 *             use them and do not change its value.
	 */
	protected int VGAP = 3;
	/**
	 * @deprecated this variable was left as protected by mistake. It will be
	 *             turned into static and hidden in the future versions. Do not
	 *             use it and do not change its value.
	 */
	protected int GAP = 4;
	static final int IGAP = 4;
	static final int IVGAP = 3;
	private static final Point NULL_SIZE = new Point(0, 0);
	private static final int VSPACE = 3;
	private static final int SEPARATOR_HEIGHT = 2;
	private int expansionStyle = TWISTIE | FOCUS_TITLE | EXPANDED;
	private boolean expanded;
	private Control textClient;
	private Control client;
	private ListenerList listeners = new ListenerList();
	private Color titleBarForeground;
	private class ExpandableLayout extends Layout implements ILayoutExtension {