Bug 30170 [Preferences] editors preferences not stored on OK?
20030121 my eclipse hard-crashed and it seems that the 'number of open editors' preference was lost preference pages should store their values on OK. i guess the 'Editors' page forgot to do it.
bundles/org.eclipse.jface/src/org/eclipse/jface/preference/PreferenceDialog.java
*/
	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.
	 *
	 * @see #pageContainer
	 */
	private class PageLayout extends Layout {
		public void layout(Composite composite, boolean force) {
			Rectangle rect = composite.getClientArea();
			Control[] children = composite.getChildren();
			for (int i = 0; i < children.length; i++) {