Setting this property also sets the Part.Visibility property to either Visibility.Visible or Visibility.Collapsed.
This dependency property is set by Node methods for collapsing/expanding subtrees, by Group methods for collapsing/expanding subgraphs, and by the PartManager as the model changes. Therefore one-way data-bindings of this attached dependency property to updated source properties may not get updated values when there are collapsed subtrees or collapsed subgraphs.
Caution: because the UIElement.Visibility of the Part may be set independently of this property, the value of this property may not reflect the value of Part.Visibility. This property is most useful in data templates for setting the initial value of Visibility for the part.