Bug 48364 PreferenceDialog can reopen empty
20031209 When you close the Preferences dialog with an entry other than the default selected you will get an empty entry in the dialog when you reopen STEPS 1) Open the preferences dialog 2) Select the Appearances page 3) Close the dialog 4) Reopen - Workbench will be selected and the contents will be empty
bundles/org.eclipse.jface/src/org/eclipse/jface/preference/PreferenceDialog.java
*/
	protected void handleShellCloseEvent() {
		
		cancelPressed();
	}
	/**
	 * Notifies of the pressing of the Help button.
	 * <p>
	 * The default implementation of this framework method
	 * calls <code>performHelp</code> on the currently active page.
	 * </p>
	 */
	protected void helpPressed() {
		if (currentPage != null) {
			currentPage.performHelp();
		}
	}
	/**
	 * Returns whether the current page is valid.
	 *
	 * @return <code>false</code> if the current page is not valid, or
	 *  or <code>true</code> if the current page is valid or there is
	 *  no current page
	*/
	protected boolean isCurrentPageValid() {
		if (currentPage == null)
			return true;
		else
			return currentPage.isValid();
	}