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
*/
	public int marginWidth = 0;
	/**
	 * Height of the margin that will be added around the control (default is
	 * 0).
	 */
	public int marginHeight = 0;
	/**
	 * Vertical spacing between the title area and the composite client control
	 * (default is 3).
	 */
	public int clientVerticalSpacing = 3;
	/**
	 * Vertical spacing between the title area and the description control
	 * (default is 0). The description control is normally placed at the new
	 * line as defined in the font used to render it. This value will be added
	 * to it.
	 * 
	 * @since 3.3
	 */
	public int descriptionVerticalSpacing = 0;
	/**
	 * Horizontal margin around the inside of the title bar area when TITLE_BAR
	 * or SHORT_TITLE_BAR style is used. This variable is not used otherwise.
	 * 
	 * @since 3.3
	 */
	public int titleBarTextMarginWidth = 6;
	/**
	 * The toggle widget used to expand the composite.