Bug 245437 [Preferences] (HEAD) Preference pages not scrollable (accessible) via keyboard
bundles/org.eclipse.jface/src/org/eclipse/jface/preference/PreferenceDialog.java
* Return code used when dialog failed
	 */
	protected static final int FAILED = 2;
	
	/**
	 * The current preference page, or <code>null</code> if there is none.
	 */
	private IPreferencePage currentPage;
	private DialogMessageArea messageArea;
	private Point lastShellSize;
	private IPreferenceNode lastSuccessfulNode;
	/**
	 * The minimum page size; 400 by 400 by default.
	 * 
	 * @see #setMinimumPageSize(Point)
	 */
	private Point minimumPageSize = new Point(400, 400);
	/**
	 * The OK button.
	 */
	private Button okButton;
	/**
	 * The Composite in which a page is shown.
	 */
	private Composite pageContainer;
	/**
	 * The preference manager.
	 */
	private PreferenceManager preferenceManager;
	/**