Move *everything* from setting flyout content and the flyout icons to a UWP control and simplified creation of the wpf host via a NotificationFlyoutApplication where you only need to set the UWP flyout

src/NotificationFlyout.Shared.UI/Class1.cs

@@ -0,0 +1,29 @@
+using System;
+using System.Drawing;
+
+namespace NotificationFlyout.Shared.UI
+{
+    public static class ImageSourceExtensions
+    {
+        public static Icon ConvertToIcon(this ImageSource imageSource, uint dpi)
+        {
+            if (imageSource == null) return null;
+
+            var uri = new Uri(imageSource.ToString(), UriKind.RelativeOrAbsolute);
+
+            var streamResource = Application.GetResourceStream(uri);
+            if (streamResource == null) throw new ArgumentException(nameof(streamResource));
+
+            return new Icon(streamResource.Stream, new System.Drawing.Size(PInvoke.GetSystemMetricsForDpi((int)SystemMetricFlag.SM_CXICON, dpi), PInvoke.GetSystemMetricsForDpi((int)SystemMetricFlag.SM_CYICON, dpi)));
+        }
+
+        private enum SystemMetricFlag : int
+        {
+            SM_CXICON = 11,
+            SM_CYICON = 12,
+            SM_CXSMICON = 49,
+            SM_CYSMICON = 50
+        }
+    }
+
+}