Reorg window handling and add drag handler

TheXamlGuy.TaskbarGroup.Flyout.Foundation/Drag.cs

@@ -0,0 +1,9 @@
+using Windows.UI.Xaml;
+
+namespace TheXamlGuy.TaskbarGroup.Flyout.Foundation
+{
+    public record class Drag<TTarget>(DragEventArgs DragEventArgs) where TTarget : UIElement
+    {
+        public TTarget Target { get; }
+    }
+}

TheXamlGuy.TaskbarGroup.Flyout.Foundation/DropTarget.cs

@@ -30,20 +30,34 @@ namespace TheXamlGuy.TaskbarGroup.Flyout.Foundation
             base.OnAttached();
         }
 
-        private void OnDrop(object sender, DragEventArgs args)
+        private object CreateDragMessage(object sender, DragEventArgs args)
         {
-            if (Mediator is not null)
-            {
-                var dropMessageType = typeof(Drop<>).MakeGenericType(sender.GetType());
-                var dropMessage = Activator.CreateInstance(dropMessageType, args);
+            var dropMessageType = typeof(Drag<>).MakeGenericType(sender.GetType());
+            return Activator.CreateInstance(dropMessageType, args);
+        }
 
-                Mediator.HandleAsync(dropMessage);            
-            }
+        private object CreateDropMessage(object sender, DragEventArgs args)
+        {
+            var dropMessageType = typeof(Drop<>).MakeGenericType(sender.GetType());
+            return Activator.CreateInstance(dropMessageType, args);
         }
 
         private void OnDragOver(object sender, DragEventArgs args)
         {
-            args.AcceptedOperation = DataPackageOperation.Link;
+            if (Mediator is not null)
+            {
+                var message = CreateDragMessage(sender, args);
+                Mediator.HandleAsync(message);
+            }
+        }
+
+        private void OnDrop(object sender, DragEventArgs args)
+        {
+            if (Mediator is not null)
+            {
+                var message = CreateDropMessage(sender, args);
+                Mediator.HandleAsync(message);
+            }
         }
     }
 }

TheXamlGuy.TaskbarGroup.Flyout.Foundation/IDragHandler.cs

@@ -0,0 +1,10 @@
+using TheXamlGuy.TaskbarGroup.Core;
+using Windows.UI.Xaml;
+
+namespace TheXamlGuy.TaskbarGroup.Flyout.Foundation
+{
+    public interface IDragHandler<TTarget> : IAsyncMessageHandler<Drag<TTarget>> where TTarget : UIElement
+    {
+
+    }
+}

TheXamlGuy.TaskbarGroup.Flyout.Foundation/TheXamlGuy.TaskbarGroup.Flyout.Foundation.csproj

@@ -122,10 +122,12 @@
     <RestoreProjectStyle>PackageReference</RestoreProjectStyle>
   </PropertyGroup>
   <ItemGroup>
+    <Compile Include="Drag.cs" />
     <Compile Include="DropTarget.cs" />
     <Compile Include="DataTemplateFactory.cs" />
     <Compile Include="Drop.cs" />
     <Compile Include="IDataTemplateFactory.cs" />
+    <Compile Include="IDragHandler.cs" />
     <Compile Include="IDropHandler.cs" />
     <Compile Include="IServiceCollectionExtensions.cs" />
     <Compile Include="IWindowPrivate.cs" />