public void SelectElements( 
   IReadOnlyList<Element> elements
)

//Set the layout's element selection.

await QueuedTask.Run(() =>
{
  Element rec = layoutView.Layout.FindElement("Rectangle");
  Element rec2 = layoutView.Layout.FindElement("Rectangle 2");

  List<Element> elmList = new List<Element>();
  elmList.Add(rec);
  elmList.Add(rec2);

  layoutView.SelectElements(elmList);
});

//This example references the active layout view.  Next it finds a couple of elements and adds them to a collection. 
//The elements in the collection are selected within the layout view.  Finally, the layout view is zoomed to the
//extent of the selection.

// Make sure the active pane is a layout view and then reference it
if (LayoutView.Active != null)
{
  LayoutView lytView = LayoutView.Active;
  //Reference the layout associated with the layout view
  Layout lyt = await QueuedTask.Run(() => lytView.Layout);

  //Find a couple of layout elements and add them to a collection
  Element map1 = lyt.FindElement("Map1 Map Frame");
  Element map2 = lyt.FindElement("Map2 Map Frame");
  List<Element> elmList = new List<Element>();
  elmList.Add(map1);
  elmList.Add(map2);

  //Set the selection on the layout view and zoom to the selected elements
  await QueuedTask.Run(() => lytView.SelectElements(elmList));
  await QueuedTask.Run(() => lytView.ZoomToSelectedElements());
}

// Make sure the active pane is a layout view and then reference it
if (LayoutView.Active != null)
{
  LayoutView lytView = LayoutView.Active;
  //Reference the layout associated with the layout view
  Layout lyt = await QueuedTask.Run(() => lytView.Layout);

  //Find a couple of layout elements and add them to a collection
  Element map1 = lyt.FindElement("Map1 Map Frame");
  Element map2 = lyt.FindElement("Map2 Map Frame");
  List<Element> elmList = new List<Element>();
  elmList.Add(map1);
  elmList.Add(map2);

  //Set the selection on the layout view and zoom to the selected elements
  await QueuedTask.Run(() => lytView.SelectElements(elmList));
  await QueuedTask.Run(() => lytView.ZoomToSelectedElements());
  return true;
}
return false;

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

//Reference the active view 
LayoutView activeLayoutView = LayoutView.Active;
if (activeLayoutView != null)
{

  //Perform on the worker thread
  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);
  });
}