Add project files.

Framework/WPF/Markups/NavigationParameter.cs

@@ -0,0 +1,17 @@
+using System.Windows;
+
+namespace TheXamlGuy.Framework.WPF
+{
+    public class NavigationParameter : DependencyObject
+    {
+        public static readonly DependencyProperty ValueProperty =
+            DependencyProperty.Register(nameof(Value),
+                typeof(object), typeof(NavigationParameter));
+
+        public object Value
+        {
+            get => GetValue(ValueProperty);
+            set => SetValue(ValueProperty, value);
+        }
+    }
+}