Android strangeness with GestureRecognizer and Nexus 9 and Nexus 7

On the Nexus 9 and Nexus 7, the values returned by MotionEvent.GetX() and MotionEvent.GetY() are larger than they should be. On other devices, it's fine. I've gotten this down to a reproducible bit of code.

Here's the code for a custom view. Whenever the renderer calls the MoveBox() method, it moves the box to the location of the tap.

    public class CustomView : AbsoluteLayout
    {
        BoxView bv;
        public CustomView()
        {
            this.HorizontalOptions = LayoutOptions.FillAndExpand;
            this.VerticalOptions = LayoutOptions.FillAndExpand;
            this.BackgroundColor = Color.Blue;
            bv = new BoxView();
            bv.Color = Color.Pink;
            Children.Add(bv);
            AbsoluteLayout.SetLayoutBounds(bv, new Rectangle(0, 0, 40, 40));
        }
        public void MoveBox(double x, double y)
        {
            AbsoluteLayout.SetLayoutBounds(bv, new Rectangle(x, y, 40, 40));
        }
    }

    public class App : Application
    {
        public App()
        {
            // The root page of your application
            MainPage = new ContentPage
            {
                Content = new StackLayout
                {
                    VerticalOptions = LayoutOptions.FillAndExpand,
                    HorizontalOptions = LayoutOptions.FillAndExpand,
                    Children = {
                        new CustomView {
                            }
                    }
                }
            };
        }

        protected override void OnStart()
        {
            // Handle when your app starts
        }

        protected override void OnSleep()
        {
            // Handle when your app sleeps
        }

        protected override void OnResume()
        {
            // Handle when your app resumes
        }
    }

And here's the code for the renderer:

using System;

using Android.App;
using Android.Content.PM;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Android.OS;

using Xamarin.Forms.Platform.Android;

[assembly: Xamarin.Forms.ExportRenderer(typeof(Android_GestureRecognizer.CustomView), typeof(Android_GestureRecognizer.Droid.CustomViewRenderer))]

namespace Android_GestureRecognizer.Droid
{

    public class CustomViewRenderer : VisualElementRenderer<Android_GestureRecognizer.CustomView>, GestureDetector.IOnGestureListener
    {
        private GestureDetector _g;

        public CustomViewRenderer()
        {
            _g = new GestureDetector(this);
        }

        private CustomView theview // TODO
        {
            get
            {
                return Element;
            }
        }
        public bool OnSingleTapUp(MotionEvent ev)
        {
            //Tell the view to move the BoxView.
            theview.MoveBox(ev.GetX(), ev.GetY());
            return true;
        }

        public void OnLongPress(MotionEvent ev)
        {
        }

        public void OnShowPress(MotionEvent ev)
        {
        }

        public bool OnFling(MotionEvent ev1, MotionEvent ev2, float vx, float vy)
        {
            return false;
        }

        public bool OnDown(MotionEvent ev)
        {
            return false;
        }

        public bool OnScroll(MotionEvent ev1, MotionEvent ev2, float dx, float dy)
        {
            return false;
        }

        public override bool OnTouchEvent(MotionEvent e)
        {
            bool b = _g.OnTouchEvent(e);
            if (b)
            {
                return true;
            }
            else
            {
                return base.OnTouchEvent(e);
            }
        }
    }


    [Activity(Label = "Android_GestureRecognizer", Icon = "@drawable/icon", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation)]
    public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsApplicationActivity
    {
        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            global::Xamarin.Forms.Forms.Init(this, bundle);
            LoadApplication(new App());
        }
    }
}