SettingsClosePopoutsOnUnload Property

Specifies if all popouts should be closed when the page that created them is closed. Popouts don't have a strong dependency on their parent and can exist on their own, but can be quite annoying to close by hand.In addition, any changes made to popouts won't be stored after the parent is closed. Default: true

public Nullable<bool> ClosePopoutsOnUnload { get; set; }