replace v6 with experimental v7 code

src/MpvNet.Windows/WPF/Msg.cs

@@ -0,0 +1,51 @@
+
+using System.Threading;
+using System.Windows;
+
+using Forms = System.Windows.Forms;
+
+using MpvNet.Windows.WPF.MsgBox;
+
+namespace MpvNet.Windows.WPF;
+
+public class Msg
+{
+    public static void ShowInfo(object msg) => Show(msg, MessageBoxImage.Information);
+
+    public static void ShowError(object msg) => Show(msg, MessageBoxImage.Error);
+
+    public static void ShowWarning(object msg) => Show(msg, MessageBoxImage.Warning);
+
+    public static MessageBoxResult ShowQuestion(object msg,
+        MessageBoxButton buttons = MessageBoxButton.OKCancel)
+    {
+        return Show(msg, MessageBoxImage.Question, buttons);
+    }
+
+    public static void ShowException(Exception exception)
+    {
+        Show(exception.Message, MessageBoxImage.Error, MessageBoxButton.OK, exception.ToString());
+    }
+
+    public static MessageBoxResult Show(
+        object msg,
+        MessageBoxImage img,
+        MessageBoxButton buttons = MessageBoxButton.OK,
+        string? details = null)
+    {
+        ApartmentState state = Thread.CurrentThread.GetApartmentState();
+       
+        if (state == ApartmentState.STA)
+            return fn();
+        else
+            return Application.Current.Dispatcher.Invoke(fn);
+
+        MessageBoxResult fn()
+        {
+            MessageBoxEx.DetailsText = details;
+
+            return MessageBoxEx.OpenMessageBox((msg + "").Trim(),
+                Forms.Application.ProductName, buttons, img);
+        }
+    }
+}