public static Task<ILayoutPane> CreateLayoutPaneAsync( 
   PaneCollection paneCollection,
   Layout layout
)

//This example creates a new layout using a minimum set of parameters.

//Added references
using ArcGIS.Desktop.Layouts;                    
using ArcGIS.Desktop.Framework.Threading.Tasks; 
using ArcGIS.Desktop.Core;

public class CreateLayoutEx1
{
  async public static Task<Layout> CreateBasicLayout(double width, double height, LinearUnit units, string LayoutName)
  {
    Layout layout = null;
    await QueuedTask.Run(() =>
    {
      layout = LayoutFactory.Instance.CreateLayout(width, height, units);
      layout.SetName(LayoutName);
    });

    //Open the layout in a pane on the UI!
    await ProApp.Panes.CreateLayoutPaneAsync(layout);

    return layout;
  }
}

//This example creates a new layout using a CIM page definion with rulers and guides included.

//Added references
using ArcGIS.Desktop.Layouts;                      
using ArcGIS.Desktop.Framework.Threading.Tasks;    
using ArcGIS.Desktop.Core;
using ArcGIS.Core.CIM;

public class CreateLayoutEx2
{
  async public static Task<Layout> CreateCIMLayout(double width, double height, LinearUnit units, string LayoutName)
  {
    Layout CIMlayout = null;
    await QueuedTask.Run(() =>
    {
      //Set up a page
      CIMPage newPage = new CIMPage();

      //required
      newPage.Width = width;
      newPage.Height = height;
      newPage.Units = units;

      //optional rulers
      newPage.ShowRulers = true;
      newPage.SmallestRulerDivision = 5;

      //optional guides
      newPage.ShowGuides = true;
      CIMGuide guide1 = new CIMGuide();
      guide1.Position = 25;
      guide1.Orientation = Orientation.Vertical;
      CIMGuide guide2 = new CIMGuide();
      guide2.Position = 185;
      guide2.Orientation = Orientation.Vertical;
      CIMGuide guide3 = new CIMGuide();
      guide3.Position = 25;
      guide3.Orientation = Orientation.Horizontal;
      CIMGuide guide4 = new CIMGuide();
      guide4.Position = 272;
      guide4.Orientation = Orientation.Horizontal;

      List<CIMGuide> guideList = new List<CIMGuide>();
      guideList.Add(guide1);
      guideList.Add(guide2);
      guideList.Add(guide3);
      guideList.Add(guide4);
      newPage.Guides = guideList.ToArray();

      Layout layout = LayoutFactory.Instance.CreateLayout(newPage);

      layout.SetName(LayoutName);
    });

    //Open the layout in a pane on the UI!
    await ProApp.Panes.CreateLayoutPaneAsync(CIMlayout);
    return CIMlayout;
  }
}

//This sample checks to see if a layout project item already has an open application pane.  
//If it does, it checks if it is the active layout view, if not, it creates, activates and opens a new pane.

//Reference a layoutitem in a project by name
LayoutProjectItem layoutItem = Project.Current.GetItems<LayoutProjectItem>().FirstOrDefault(item => item.Name.Equals("Layout View"));

//Get the layout associated with the layoutitem
Layout lyt = await QueuedTask.Run(() => layoutItem.GetLayout());
      
//Iterate through each pane in the application and check to see if the layout is already open and if so, activate it
foreach (var pane in ProApp.Panes)
{
  var layoutPane = pane as ILayoutPane;
  if (layoutPane == null)  //if not a layout pane, continue to the next pane
    continue;
  if (layoutPane.LayoutView.Layout == lyt)  //if the layout pane does match the layout, activate it.
  {
    (layoutPane as Pane).Activate();
    layoutPane.Caption = "This is a test";
    System.Windows.MessageBox.Show(layoutPane.Caption);
    return;
  }
}
//Otherwise, create, open, and activate the layout if not already open
ILayoutPane newPane = await ProApp.Panes.CreateLayoutPaneAsync(lyt);

//Zoom to the full extent of the layout
await QueuedTask.Run(() => newPane.LayoutView.ZoomTo100Percent());

//Open a layout project item in a new view.
//A layout project item may exist but it may not be open in a view. 

//Reference a layout project item by name
LayoutProjectItem someLytItem = Project.Current.GetItems<LayoutProjectItem>()
                          .FirstOrDefault(item => item.Name.Equals("MyLayout"));

//Get the layout associated with the layout project item
Layout layout = await QueuedTask.Run(() => someLytItem.GetLayout());  //Worker thread

//Create the new pane - call on UI
ILayoutPane iNewLayoutPane = await ProApp.Panes.CreateLayoutPaneAsync(layout); //GUI thread

//Create a new, basic layout and open it.

//Create layout with minimum set of parameters on the worker thread
Layout lyt = await QueuedTask.Run(() =>
{
  var newLayout = LayoutFactory.Instance.CreateLayout(8.5, 11, LinearUnit.Inches);
  newLayout.SetName("New 8.5x11 Layout");
  return newLayout;
});
      
//Open new layout on the GUI thread
await ProApp.Panes.CreateLayoutPaneAsync(lyt);

//Create a new layout using a modified CIM and open it.
//The CIM exposes additional members that may not be
//available through the managed API.  
//In this example, optional guides are added.

//Create a new CIMLayout on the worker thread
Layout newCIMLayout = await QueuedTask.Run(() =>
{
  //Set up a CIM page
  CIMPage newPage = new CIMPage
  {
    //required parameters
    Width = 8.5,
    Height = 11,
    Units = LinearUnit.Inches,

    //optional rulers
    ShowRulers = true,
    SmallestRulerDivision = 0.5,

    //optional guides
    ShowGuides = true
  };
  CIMGuide guide1 = new CIMGuide
  {
    Position = 1,
    Orientation = Orientation.Vertical
  };
  CIMGuide guide2 = new CIMGuide
  {
    Position = 6.5,
    Orientation = Orientation.Vertical
  };
  CIMGuide guide3 = new CIMGuide
  {
    Position = 1,
    Orientation = Orientation.Horizontal
  };
  CIMGuide guide4 = new CIMGuide
  {
    Position = 10,
    Orientation = Orientation.Horizontal
  };

  List<CIMGuide> guideList = new List<CIMGuide>
  {
    guide1,
    guide2,
    guide3,
    guide4
  };
  newPage.Guides = guideList.ToArray();

  //Construct the new layout using the customized cim definitions
  var layout_local = LayoutFactory.Instance.CreateLayout(newPage);
  layout_local.SetName("New 8.5x11 Layout");
  return layout_local;
});

//Open new layout on the GUI thread
await ProApp.Panes.CreateLayoutPaneAsync(newCIMLayout);