Bug 36141 Misbehaving property page causes property dialog to fail to open
bundles/org.eclipse.jface/src/org/eclipse/jface/preference/PreferenceDialog.java
* The OK button.
	 */
	private Button okButton;
	/**
	 * The Cancel button.
	 */
	private Button cancelButton;
	/**
	 * The Help button; <code>null</code> if none.
	 */
	private Button helpButton = null;
	/**
	 * Indicates whether help is available; <code>false</code> by default.'
	 *
	 * @see #setHelpAvailable
	 */
	private boolean isHelpAvailable = false;
	/**
	 * The tree control.
	 */
	private Tree tree;
	/**
	 * The current tree item.
	 */
	private TreeItem currentTreeItem;
	/**
	 * Layout for the page container.
	 *
	 */
	private class PageLayout extends Layout {