feat(Window): Allow to persist content of Clipboard after App close

src/Android/Avalonia.Android/Platform/ClipboardImpl.cs

@@ -55,5 +55,8 @@ namespace Avalonia.Android.Platform
         public Task<string[]> GetFormatsAsync() => throw new PlatformNotSupportedException();
 
         public Task<object?> GetDataAsync(string format) => throw new PlatformNotSupportedException();
+
+        /// <inheritdoc />
+        public Task SetDataObjectAsync(IDataObject data, bool copy) => throw new PlatformNotSupportedException();
     }
 }

src/Avalonia.Base/Input/Platform/IClipboard.cs

@@ -6,16 +6,50 @@ namespace Avalonia.Input.Platform
     [NotClientImplementable]
     public interface IClipboard
     {
+        /// <summary>
+        /// Returns a string containing the text data on the Clipboard.
+        /// </summary>
+        /// <returns>A string containing text data in the specified data format, or an empty string if no corresponding text data is available.</returns>
         Task<string?> GetTextAsync();
 
+        /// <summary>
+        /// Stores text data on the Clipboard. The text data to store is specified as a string.
+        /// </summary>
+        /// <param name="text">A string that contains the UnicodeText data to store on the Clipboard.</param>
+        /// <exception cref="System.ArgumentNullException"><paramref name="text"/> is null.</exception>
         Task SetTextAsync(string? text);
 
+        /// <summary>
+        /// Clears any data from the system Clipboard.
+        /// </summary>
         Task ClearAsync();
 
+        /// <summary>
+        /// Places a specified non-persistent data object on the system Clipboard.
+        /// </summary>
+        /// <param name="data">A data object (an object that implements <see cref="IDataObject"/>) to place on the system Clipboard.</param>
+        /// <exception cref="System.ArgumentNullException"><paramref name="data"/> is null.</exception>
         Task SetDataObjectAsync(IDataObject data);
-        
+
+        /// <summary>
+        /// Places a specified data object on the system Clipboard and accepts a Boolean parameter that indicates whether the data object should be left on the Clipboard when the application exits.
+        /// </summary>
+        /// <param name="data">A data object (an object that implements <see cref="IDataObject"/>) to place on the system Clipboard.</param>
+        /// <param name="copy"><c>true</c> to leave the data on the system Clipboard when the application exits; false to clear the data from the system Clipboard when the application exits.</param>
+        /// <exception cref="System.ArgumentNullException"><paramref name="data"/> is null.</exception>
+        Task SetDataObjectAsync(IDataObject data, bool copy);
+
+
+        /// <summary>
+        /// Get list of available Clipboard format.
+        /// </summary>
         Task<string[]> GetFormatsAsync();
-        
+
+        /// <summary>
+        /// Retrieves data in a specified format from the Clipboard.
+        /// </summary>
+        /// <param name="format">A string that specifies the format of the data to retrieve. For a set of predefined data formats, see the <see cref="DataFormats"/> class.</param>
+        /// <returns></returns>
         Task<object?> GetDataAsync(string format);
     }
 }

src/Avalonia.DesignerSupport/Remote/Stubs.cs

@@ -208,6 +208,7 @@ namespace Avalonia.DesignerSupport.Remote
 
         public Task ClearAsync() => Task.CompletedTask;
         public Task SetDataObjectAsync(IDataObject data) => Task.CompletedTask;
+        public Task SetDataObjectAsync(IDataObject data, bool copy) => Task.CompletedTask;
         public Task<string[]> GetFormatsAsync() => Task.FromResult(Array.Empty<string>());
 
         public Task<object> GetDataAsync(string format) => Task.FromResult((object)null);

src/Avalonia.Native/ClipboardImpl.cs

@@ -9,7 +9,6 @@ using Avalonia.Logging;
 using Avalonia.Native.Interop;
 using Avalonia.Platform.Storage;
 using Avalonia.Platform.Storage.FileIO;
-using MicroCom.Runtime;
 
 namespace Avalonia.Native
 {
@@ -156,6 +155,9 @@ namespace Avalonia.Native
             return Task.CompletedTask;
         }
 
+        ///
+        public Task SetDataObjectAsync(IDataObject data, bool copy) => throw new PlatformNotSupportedException();
+
         public Task<string[]> GetFormatsAsync()
         {
             return Task.FromResult(GetFormats().ToArray());

src/Avalonia.X11/X11Clipboard.cs

@@ -302,10 +302,12 @@ namespace Avalonia.X11
         public Task SetDataObjectAsync(IDataObject data)
         {
             _storedDataObject = data;
-            XSetSelectionOwner(_x11.Display, _x11.Atoms.CLIPBOARD, _handle, IntPtr.Zero);            
+            XSetSelectionOwner(_x11.Display, _x11.Atoms.CLIPBOARD, _handle, IntPtr.Zero);
             return StoreAtomsInClipboardManager(data);
         }
 
+        public Task SetDataObjectAsync(IDataObject data, bool copy) => throw new PlatformNotSupportedException();
+
         public async Task<string[]> GetFormatsAsync()
         {
             if (!HasOwner)

src/Browser/Avalonia.Browser/ClipboardImpl.cs

@@ -22,6 +22,8 @@ namespace Avalonia.Browser
 
         public Task SetDataObjectAsync(IDataObject data) => Task.CompletedTask;
 
+        /// <inheritdoc />
+        public Task SetDataObjectAsync(IDataObject data, bool copy) => Task.CompletedTask;
         public Task<string[]> GetFormatsAsync() => Task.FromResult(Array.Empty<string>());
 
         public Task<object?> GetDataAsync(string format) => Task.FromResult<object?>(null);

src/Headless/Avalonia.Headless/HeadlessPlatformStubs.cs

@@ -6,18 +6,12 @@ using System.IO;
 using System.Linq;
 using System.Runtime.InteropServices;
 using System.Threading.Tasks;
-using Avalonia.Controls;
-using Avalonia.Controls.Platform;
 using Avalonia.Input;
 using Avalonia.Input.Platform;
 using Avalonia.Media;
-using Avalonia.Media.Fonts;
 using Avalonia.Media.TextFormatting;
 using Avalonia.Media.TextFormatting.Unicode;
 using Avalonia.Platform;
-using Avalonia.Platform.Storage;
-using Avalonia.Platform.Storage.FileIO;
-using Avalonia.Utilities;
 
 namespace Avalonia.Headless
 {
@@ -41,10 +35,11 @@ namespace Avalonia.Headless
             return Task.Run(() => _text = null);
         }
 
-        public Task SetDataObjectAsync(IDataObject data)
-        {
-            return Task.Run(() => _data = data);
-        }
+        public Task SetDataObjectAsync(IDataObject data) =>
+            SetDataObjectAsync(data, false);
+
+        public Task SetDataObjectAsync(IDataObject data, bool copy) =>
+            Task.Run(() => _data = data);
 
         public Task<string[]> GetFormatsAsync()
         {

src/Tizen/Avalonia.Tizen/NuiClipboardImpl.cs

@@ -65,6 +65,8 @@ internal class NuiClipboardImpl : IClipboard
         });
     }
 
+    public Task SetDataObjectAsync(IDataObject data, bool copy) => throw new PlatformNotSupportedException();
+
     public Task<object?> GetDataAsync(string format) =>
         throw new PlatformNotSupportedException();
 

src/Windows/Avalonia.Win32/ClipboardImpl.cs

@@ -1,10 +1,10 @@
 using System;
 using System.Linq;
-using Avalonia.Reactive;
 using System.Runtime.InteropServices;
 using System.Threading.Tasks;
 using Avalonia.Input;
 using Avalonia.Input.Platform;
+using Avalonia.Reactive;
 using Avalonia.Threading;
 using Avalonia.Win32.Interop;
 using MicroCom.Runtime;
@@ -15,6 +15,13 @@ namespace Avalonia.Win32
     {
         private const int OleRetryCount = 10;
         private const int OleRetryDelay = 100;
+        /// <summary>
+        /// The amount of time in milliseconds to sleep before flushing the clipboard after a set.
+        /// </summary>
+        /// <remarks>
+        /// This is mitigation for clipboard listener issues.
+        /// </remarks>
+        private const int OleFlushDelay = 10;
 
         private static async Task<IDisposable> OpenClipboard()
         {
@@ -32,7 +39,7 @@ namespace Avalonia.Win32
 
         public async Task<string?> GetTextAsync()
         {
-            using(await OpenClipboard())
+            using (await OpenClipboard())
             {
                 IntPtr hText = UnmanagedMethods.GetClipboardData(UnmanagedMethods.ClipboardFormat.CF_UNICODETEXT);
                 if (hText == IntPtr.Zero)
@@ -54,7 +61,7 @@ namespace Avalonia.Win32
 
         public async Task SetTextAsync(string? text)
         {
-            using(await OpenClipboard())
+            using (await OpenClipboard())
             {
                 UnmanagedMethods.EmptyClipboard();
 
@@ -68,13 +75,16 @@ namespace Avalonia.Win32
 
         public async Task ClearAsync()
         {
-            using(await OpenClipboard())
+            using (await OpenClipboard())
             {
                 UnmanagedMethods.EmptyClipboard();
             }
         }
 
-        public async Task SetDataObjectAsync(IDataObject data)
+        public async Task SetDataObjectAsync(IDataObject data) =>
+            await SetDataObjectAsync(data, false);
+
+        public async Task SetDataObjectAsync(IDataObject data, bool copy)
         {
             Dispatcher.UIThread.VerifyAccess();
             using var wrapper = new DataObject(data);
@@ -90,9 +100,21 @@ namespace Avalonia.Win32
 
                 if (--i == 0)
                     Marshal.ThrowExceptionForHR(hr);
-                
+
                 await Task.Delay(OleRetryDelay);
             }
+
+            if (copy)
+            {
+                // OleSetClipboard and OleFlushClipboard both modify the clipboard
+                // and cause notifications to be sent to clipboard listeners. We sleep a bit here to
+                // mitigate issues with clipboard listeners (like TS) corrupting the clipboard contents
+                // as a result of these two calls being back to back.
+                await Task.Delay(OleFlushDelay);
+
+                await FlushAsync();
+            }
+
         }
 
         public async Task<string[]> GetFormatsAsync()
@@ -142,5 +164,32 @@ namespace Avalonia.Win32
                 await Task.Delay(OleRetryDelay);
             }
         }
+
+        /// <summary>
+        /// Permanently renders the contents of the last IDataObject that was set onto the clipboard.
+        /// </summary>
+        private static async Task FlushAsync()
+        {
+            // Retry OLE operations several times as mitigation for clipboard locking issues in TS sessions.
+
+            int i = OleRetryCount;
+
+            while (true)
+            {
+                var hr = UnmanagedMethods.OleFlushClipboard();
+
+                if (hr == 0)
+                {
+                    break;
+                }
+
+                if (--i == 0)
+                {
+                    Marshal.ThrowExceptionForHR(hr);
+                }
+
+                await Task.Delay(OleRetryDelay);
+            }
+        }
     }
 }

src/Windows/Avalonia.Win32/Interop/UnmanagedMethods.cs

@@ -1570,6 +1570,8 @@ namespace Avalonia.Win32.Interop
 
         [DllImport("ole32.dll", PreserveSig = true)]
         public static extern int OleGetClipboard(out IntPtr dataObject);
+        [DllImport("ole32.dll", PreserveSig = true)]
+        public static extern int OleFlushClipboard();
 
         [DllImport("ole32.dll", PreserveSig = true)]
         public static extern int OleSetClipboard(IntPtr dataObject);

tests/Avalonia.Controls.UnitTests/MaskedTextBoxTests.cs

@@ -990,9 +990,14 @@ namespace Avalonia.Controls.UnitTests
 
             public Task SetDataObjectAsync(IDataObject data) => Task.CompletedTask;
 
+            public Task SetDataObjectAsync(IDataObject data, bool copy) => Task.CompletedTask;
+
             public Task<string[]> GetFormatsAsync() => Task.FromResult(Array.Empty<string>());
 
             public Task<object> GetDataAsync(string format) => Task.FromResult((object)null);
+
+
+           
         }
 
         private class TestTopLevel : TopLevel

tests/Avalonia.Controls.UnitTests/TextBoxTests.cs

@@ -1651,10 +1651,12 @@ namespace Avalonia.Controls.UnitTests
             }
             
             public Task SetDataObjectAsync(IDataObject data) => Task.CompletedTask;
-
+            public Task SetDataObjectAsync(IDataObject data, bool copy) => Task.CompletedTask;
             public Task<string[]> GetFormatsAsync() => Task.FromResult(Array.Empty<string>());
 
             public Task<object> GetDataAsync(string format) => Task.FromResult((object)null);
+
+
         }
 
         private class TestTopLevel : TopLevel