Gets or sets if new items, added to the BarManager object after a customized layout is saved to an .xml file, will remain after restoring this layout. This is a dependency property.
true if new items will remain after a layout is restored from an .xml file; otherwise, false.
When restoring a previously saved custom layout, any changes that were made after saving a layout will be discarded. So, the layout you get is, in fact, the one that was previously saved. You can combine both the restored and the new custom layout by setting the AddNewItems property to true. In this case, newly added items won't be removed after restoring a custom layout.