Use UI thread for setting clipboard text - fixes #457

Author: GrahamTheCoder

Vsix/CodeConversion.cs

@@ -66,13 +66,20 @@ await _joinableTaskFactory.RunAsync(async () => {
             });
 
             if ((await GetOptions()).CopyResultToClipboardForSingleDocument) {
-                Clipboard.SetText(conversionResult.ConvertedCode ?? conversionResult.GetExceptionsAsString());
+                await SetClipboardTextOnUiThreadAsync(conversionResult.ConvertedCode ?? conversionResult.GetExceptionsAsString());
                 await _outputWindow.WriteToOutputWindowAsync(Environment.NewLine + "Conversion result copied to clipboard.");
                 await VisualStudioInteraction.ShowMessageBoxAsync(_serviceProvider, "Conversion result copied to clipboard.", conversionResult.GetExceptionsAsString(), false);
             }
 
         }
 
+        private static async Task SetClipboardTextOnUiThreadAsync(string conversionResultConvertedCode)
+        {
+            await ThreadHelper.JoinableTaskFactory.SwitchToMainThreadAsync();
+            Clipboard.SetText(conversionResultConvertedCode);
+            await TaskScheduler.Default;
+        }
+
         private async Task WriteConvertedFilesAndShowSummaryAsync(IEnumerable<ConversionResult> convertedFiles)
         {
             await _outputWindow.WriteToOutputWindowAsync(Intro, true, true);