public void SetMargin( 
   CIMMargin margin
)

// create customized margin and color 
CIMMargin pMargin = new CIMMargin() { Left = 0.2, Right = 0.3, Top = 0.15, Bottom = 0.25 };
CIMRGBColor pColor = new CIMRGBColor() { R = 255, G = 255, B = 0, Alpha = 50 };

//Reference a page and its transition 
var page = activePresentationView.Presentation.GetPage(0);
CIMPresentationTransition transition = page.Transition;

// update the transition style
transition.TransitionType = PresentationTransitionType.Swipe;
transition.Duration = 2.0;
transition.SwipeDirection = SwipeDirection.Top;

//Must be on the QueuedTask
await QueuedTask.Run(() =>
{
  //Set the new margin, new background color and new transition effect
  page.SetMargin(pMargin);
  page.SetBackgroundColor(pColor);
  page.SetTransition(transition);
});