Bug 218360 [Servicability] Fix places that pop up message dialogues under ISafeRunnable
bundles/org.eclipse.jface/src/org/eclipse/jface/preference/PreferenceDialog.java
}
	/**
	 * @param selection
	 *            the <code>ISelection</code> to examine.
	 * @return the first element, or null if empty.
	 */
	protected IPreferenceNode getSingleSelection(ISelection selection) {
		if (!selection.isEmpty()) {
			IStructuredSelection structured = (IStructuredSelection) selection;
			if (structured.getFirstElement() instanceof IPreferenceNode) {
				return (IPreferenceNode) structured.getFirstElement();
			}
		}
		return null;
	}
	/**
	 * @return the <code>TreeViewer</code> for this dialog.
	 * @since 3.3
	 */
	public TreeViewer getTreeViewer() {
		return treeViewer;
	}
	/**
	 * Save the values specified in the pages.
	 * <p>
	 * The default implementation of this framework method saves all pages of
	 * type <code>PreferencePage</code> (if their store needs saving and is a
	 * <code>PreferenceStore</code>).
	 * </p>
	 * <p>