// update the add-in store to include add-ins located in the 
// current program folder
string[] warnings = AddInStore.Update(PipelineStoreLocation.ApplicationBase);
// get the view type defined in the host views assembly
System.Type hostViewOfAddIn = typeof(ShapeAppHostViews.IShapeAddIn);
// find all add-ins that implement the view
ICollection<AddInToken> addIns = AddInStore.FindAddIns(hostViewOfAddIn,
    PipelineStoreLocation.ApplicationBase);

// activate the add-in in full trust mode
ShapeAppHostViews.IShapeAddIn addIn = 
    token.Activate<ShapeAppHostViews.IShapeAddIn>( 
    AddInSecurityLevel.FullTrust);

public class ShapeApplication : System.Windows.Forms.IWin32Window
{
...
}

public class ShapeApplication : ShapeAppHostViews.IShapeApplication,
    System.Windows.Forms.IWin32Window
{
...
}

public bool Visible
{
    get {...}
    set {...}
}

public Drawing ActiveDrawing
{
    get {...}
}

IDrawing ActiveDrawing
{
    get;
}

public Drawing NewDrawing()
{
    Drawing newDrawing = new Drawing(this); 
    ...
    this.ApplicationForm.drawingsTabControl.TabPages.Add(
        newDrawing.DrawingSurface);
    ... 
    return newDrawing;
}

public interface IShapeAddIn
{
    void Initialize(IShapeApplication application);
}

public interface IShapeApplication
{
    // TODO: Implement this.
}

public interface IShapeApplication
{
       ... 
       // event fired when a drawing is created 
       event EventHandler<CreatedDrawingEventArgs> CreatedDrawing;
}

public interface IShapeApplicationContract : IContract
{
    ...
    void CreatedDrawingAdd(ICreatedDrawingEventHandlerContract handler);
    void CreatedDrawingRemove(ICreatedDrawingEventHandlerContract 
        handler);
}

public interface ICreatedDrawingEventHandlerContract : IContract
{
    void Handler(ICreatedDrawingEventArgsContract args);
}

AddInForm form = new AddInForm();
form.Show();