/// <summary>
/// Called when deactivating.
/// </summary>
/// <param name="close">Inidicates whether this instance will be closed.</param>
protected override void OnDeactivate(bool close)
{
ScreenExtensions.TryDeactivate(ActiveItem, close);
}
void CloseItemCore(T item)
{
ScreenExtensions.TryDeactivate(item, true);
items.Remove(item);
}