Merge pull request #4076 from Jan18101997/develop

Fixed issue #4072
MahApps · Apr 20, 2021 · 11a5fa5 · 11a5fa5
1 parent b72af9e
commit 11a5fa5
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Showing 2 changed files with 9 additions and 11 deletions.
diff --git a/src/MahApps.Metro/Behaviors/WindowsSettingBehavior.cs b/src/MahApps.Metro/Behaviors/WindowsSettingBehavior.cs
@@ -46,15 +46,14 @@ private void AssociatedObject_SourceInitialized(object sender, EventArgs e)
             window.Closing += this.AssociatedObject_Closing;
             window.Closed += this.AssociatedObject_Closed;
 
-            // This operation must be thread safe
-            window.BeginInvoke(() =>
+            // This operation must be thread safe. It is possible, that the window is running in a different Thread.
+            Application.Current?.BeginInvoke(app =>
                 {
-                    var application = Application.Current;
-                    if (application != null)
+                    if (app != null)
                     {
-                        application.SessionEnding += this.CurrentApplicationSessionEnding;
+                        app.SessionEnding += this.CurrentApplicationSessionEnding;
                     }
-                }); 
+                });
         }
 
         private void AssociatedObject_Closing(object sender, System.ComponentModel.CancelEventArgs e)
@@ -100,12 +99,11 @@ private void CleanUp(string fromWhere)
             window.SourceInitialized -= this.AssociatedObject_SourceInitialized;
 
             // This operation must be thread safe
-            window.BeginInvoke(() =>
+            Application.Current?.BeginInvoke(app =>
                 {
-                    var application = Application.Current;
-                    if (application != null)
+                    if (app != null)
                     {
-                        application.SessionEnding -= this.CurrentApplicationSessionEnding;
+                        app.SessionEnding -= this.CurrentApplicationSessionEnding;
                     }
                 });
         }

diff --git a/src/MahApps.Metro/Controls/Extensions.cs b/src/MahApps.Metro/Controls/Extensions.cs
@@ -73,7 +73,7 @@ public static void BeginInvoke([NotNull] this DispatcherObject dispatcherObject,
                 throw new ArgumentNullException(nameof(invokeAction));
             }
 
-            dispatcherObject.Dispatcher.BeginInvoke(priority, invokeAction);
+            dispatcherObject.Dispatcher?.BeginInvoke(priority, invokeAction);
         }
 
         public static void BeginInvoke<T>([NotNull] this T dispatcherObject, [NotNull] Action<T> invokeAction, DispatcherPriority priority = DispatcherPriority.Background)