public void SelectElements( 
   IReadOnlyList<Element> elements
)

{
  //Set the active layout view's selection to include 2 rectangle elements.

  //Reference the active view 
  LayoutView activeLayoutView = LayoutView.Active;
  if (activeLayoutView != null)
  {
    //Note: Must be on QueuedTask.Run
    //Reference the layout
    Layout lyt = activeLayoutView.Layout;

    //Reference the two rectangle elements
    Element rec = lyt.FindElement("Rectangle");
    Element rec2 = lyt.FindElement("Rectangle 2");

    //Construct a list and add the elements
    List<Element> elmList = new List<Element>
    {
      rec,
      rec2
    };
    //Set the selection
    activeLayoutView.SelectElements(elmList);
  }
}