Revise assembly tree related to eliminate gaps

Author: lextm

src/ILSpy

@@ -0,0 +1,58 @@
+using System;
+using System.Collections.Generic;
+using System.Windows;
+
+namespace System.Windows
+{
+    /// <summary>
+    /// Minimal shim of WPF's DataObject for portability.
+    /// Note: This is intentionally small — only members required by the port are implemented.
+    /// </summary>
+    public class DataObject : IDataObject
+    {
+        readonly Dictionary<string, object?> storage = new Dictionary<string, object?>();
+
+        public DataObject()
+        {
+        }
+
+        public object? GetData(string format)
+        {
+            storage.TryGetValue(format, out var value);
+            return value;
+        }
+
+        public bool GetDataPresent(string format)
+        {
+            return storage.ContainsKey(format);
+        }
+
+        public void SetData(string format, object? data)
+        {
+            storage[format] = data;
+        }
+
+        public void SetText(string text)
+        {
+            SetData(DataFormats.Text, text);
+            SetData(DataFormats.UnicodeText, text);
+        }
+
+        public void SetText(string text, TextDataFormat format)
+        {
+            // only handle basic CSV or Plain text as Text
+            SetText(text);
+        }
+
+        // Pasting handler helpers (no-op for Avalonia port; provided for compile-time compatibility)
+        public static void AddPastingHandler(object target, Action<object, DataObjectPastingEventArgs> handler)
+        {
+            // No-op: Avalonia handles paste differently. Handlers in code will not be invoked.
+        }
+
+        public static void AddSettingDataHandler(object target, Action<object, DataObjectSettingDataEventArgs> handler)
+        {
+            // No-op placeholder for WPF compatibility.
+        }
+    }
+}

src/ProjectRover.Shims/SystemWindows/DataObject.cs

@@ -0,0 +1,53 @@
+using System;
+
+namespace System.Windows
+{
+    public sealed class DataObjectPastingEventArgs : EventArgs
+    {
+        public IDataObject SourceDataObject { get; }
+        public bool IsDragDrop { get; }
+        public string Format { get; }
+        public bool Cancel { get; private set; }
+
+        public DataObjectPastingEventArgs(IDataObject dataObject, bool isDragDrop, string format)
+        {
+            SourceDataObject = dataObject;
+            IsDragDrop = isDragDrop;
+            Format = format;
+        }
+
+        public void CancelCommand()
+        {
+            Cancel = true;
+        }
+    }
+
+    public sealed class DataObjectSettingDataEventArgs : EventArgs
+    {
+        public IDataObject DataObject { get; }
+        public string Format { get; }
+
+        public DataObjectSettingDataEventArgs(IDataObject dataObject, string format)
+        {
+            DataObject = dataObject;
+            Format = format;
+        }
+    }
+
+    public enum TextDataFormat
+    {
+        Text,
+        UnicodeText,
+        CommaSeparatedValue,
+        Html
+    }
+
+    public static class DataFormats
+    {
+        public const string Text = "Text";
+        public const string UnicodeText = "UnicodeText";
+        public const string FileDrop = "FileDrop";
+        public const string Html = "HTML";
+        public const string CommaSeparatedValue = "Csv";
+    }
+}

src/ProjectRover.Shims/SystemWindows/DataObjectEventShims.cs

@@ -0,0 +1,17 @@
+using System;
+
+namespace System.Windows
+{
+    /// <summary>
+    /// Minimal shim of WPF's <c>IDataObject</c> used by the port.
+    /// Only implements the members referenced by the ILSpy port.
+    /// </summary>
+    public interface IDataObject
+    {
+        object? GetData(string format);
+
+        bool GetDataPresent(string format);
+
+        void SetData(string format, object? data);
+    }
+}

src/ProjectRover.Shims/SystemWindows/IDataObject.cs

@@ -17,6 +17,11 @@ internal record ExceptionData(Exception Exception)
         }
 
         public Window MainWindow { get; set; } // TODO: proper shim
+
+        public static void UnhandledException(Exception exception)
+        {
+            // TODO:
+        }
     }
 }