fix: fire Dragover events to accompany DragEnter and Drop

src/Uno.UI/UI/Xaml/DragDrop/DragEventArgs.cs

@@ -29,6 +29,11 @@ internal DragEventArgs(
 			DragUIOverride = uiOverride;
 		}
 
+		internal DragEventArgs(DragEventArgs args) : this((UIElement)args.OriginalSource, args._info, args.DragUIOverride)
+		{
+			AcceptedOperation = args.AcceptedOperation;
+		}
+
 		#region Readonly properties that gives context to the handler
 		public bool Handled { get; set; }
 

src/Uno.UI/UI/Xaml/UIElement.Pointers.cs

@@ -792,13 +792,18 @@ private protected virtual void PrepareShare(DataPackage data)
 
 		internal void RaiseDragEnterOrOver(global::Microsoft.UI.Xaml.DragEventArgs args)
 		{
-			var evt = IsDragOver(args.SourceId)
-				? DragOverEvent
-				: DragEnterEvent;
+			var wasDragOver = IsDragOver(args.SourceId);
 
 			(_draggingOver ??= new HashSet<long>()).Add(args.SourceId);
 
-			SafeRaiseEvent(evt, args);
+			if (!wasDragOver)
+			{
+				var args2 = new DragEventArgs(args);
+				SafeRaiseEvent(DragEnterEvent, args);
+				args.AcceptedOperation = args2.AcceptedOperation;
+			}
+
+			SafeRaiseEvent(DragOverEvent, args);
 		}
 
 		internal void RaiseDragLeave(global::Microsoft.UI.Xaml.DragEventArgs args, UIElement upTo = null)
@@ -813,7 +818,14 @@ internal void RaiseDrop(global::Microsoft.UI.Xaml.DragEventArgs args)
 		{
 			if (_draggingOver?.Remove(args.SourceId) ?? false)
 			{
-				SafeRaiseEvent(DropEvent, args);
+				var args2 = new DragEventArgs(args);
+				SafeRaiseEvent(DragOverEvent, args2);
+				args.AcceptedOperation = args2.AcceptedOperation;
+				// On WinUI, if the final DragOver event sets AcceptedOperation to None, the DropEvent won't fire
+				if (args.AcceptedOperation is not DataPackageOperation.None)
+				{
+					SafeRaiseEvent(DropEvent, args);
+				}
 			}
 		}
 		#endregion