Because the TreeListNode’s IsExpanded property is not a DependencyProperty, there is no way to create TwoWay binding between the IsExpanded and data source item’s property. The example demonstrates how to emulate this functionality using behaviors.
BindableExpandingBehavior class attaches to a GridControl to provide the functionality. The BindableExpandingBehavior’s ExpandingProperty must be set and has to contain the name of the property in a data item, which will be used to expand/collapse the TreeListNode. The type of the property has to be Boolean.
The behavior will be automatically enabled for each level in TreeListView where a data item contains the same property name set in the BindableExpandingBehavior’s ExpandingProperty.
You can easily add the same functionality to your project using BindableExpandingBehavior class and attaching it as a behavior to your GridControl.