Feature [DYN-5197] dismiss NotificationsPanel by clicking outside the…

… panel (#14680)

* feat(NotificationCenterController): add PreviewMouseDown to dismiss notifications panel by clicking outside the panel

* unsuscribe DynamoView_PreviewMouseDown event handler

src/Notifications/NotificationCenterController.cs

@@ -83,6 +83,7 @@ internal NotificationCenterController(DynamoView view, DynamoLogger dynLogger)
             dynamoView.LocationChanged += DynamoView_LocationChanged;
             notificationsButton.Click += NotificationsButton_Click;
             dynamoView.Closing += View_Closing;
+            dynamoView.PreviewMouseDown += DynamoView_PreviewMouseDown;
 
             notificationUIPopup = new NotificationUI
             {
@@ -106,6 +107,7 @@ internal NotificationCenterController(DynamoView view, DynamoLogger dynLogger)
         private void View_Closing(object sender, System.ComponentModel.CancelEventArgs e)
         {
             dynamoView.Closing -= View_Closing;
+            dynamoView.PreviewMouseDown -= DynamoView_PreviewMouseDown;
             SuspendCoreWebviewAsync();
         }
 
@@ -276,6 +278,17 @@ private void DynamoView_SizeChanged(object sender, SizeChangedEventArgs e)
             notificationUIPopup.UpdatePopupLocation();
         }
 
+        /// <summary>
+        /// Dismiss notifications panel by clicking outside the panel
+        /// </summary>
+        /// <param name="sender"></param>
+        /// <param name="e"></param>
+        private void DynamoView_PreviewMouseDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
+        {
+            if (!notificationUIPopup.IsOpen) return;
+            notificationUIPopup.IsOpen = false;
+        }
+
         /// <summary>
         /// Notification Center button click handler
         /// </summary>