public ReadOnlyObservableCollection<Element> GetSelectedElements()

{
  //Note: Must be on QueuedTask.Run
  var elementsToRemove = layout.GetSelectedElements();
  layout.DeleteElements(elementsToRemove);
}

{
  //Note: Must be on QueuedTask.Run
  var elemsToGroup = layout.GetSelectedElements();
  //Note: run within the QueuedTask
  //group  elements
  var newGroupElement = layout.GroupElements(elemsToGroup);
}

{
  //Note: Must be on QueuedTask.Run
  //get the current selection set
  var sel_elems = layout.GetSelectedElements();
  //can they be brought forward? This will also check that all elements have the same parent
  if (layout.CanBringForward(sel_elems))
  {
    //bring forward
    layout.BringForward(sel_elems);
    //bring to front (of parent)
    //graphicsLayer.BringToFront(sel_elems);
  }
  else if (layout.CanSendBackward(sel_elems))
  {
    //send back
    layout.SendBackward(sel_elems);
    //send to the back (of parent)
    //graphicsLayer.SendToBack(sel_elems);
  }
}

{
  var selElementsZOrder = layout.GetSelectedElements();
  //list out the z order
  foreach (var elem in selElementsZOrder)
    System.Diagnostics.Debug.WriteLine($"{elem.Name}: z-order {elem.ZOrder}");
}