re-focus popup when updating content #320

Author: ButchersBoy

MaterialDesignThemes.Wpf/DialogHost.cs

@@ -266,17 +266,13 @@ private static void IsOpenPropertyChangedCallback(DependencyObject dependencyObj
 
             dialogHost.Dispatcher.BeginInvoke(DispatcherPriority.Background, new Action(() =>
             {
-                var child = dialogHost._popup?.Child;
-                if (child == null) return;
-
-                child.Focus();
-                child.MoveFocus(new TraversalRequest(FocusNavigationDirection.Next));
+                var child = dialogHost.FocusPopup();
 
                 //https://github.com/ButchersBoy/MaterialDesignInXamlToolkit/issues/187
                 //totally not happy about this, but on immediate validation we can get some weird looking stuff...give WPF a kick to refresh...
-                Task.Delay(300).ContinueWith(t => child.Dispatcher.BeginInvoke(new Action(() => child.InvalidateVisual())));                
+                Task.Delay(300).ContinueWith(t => child.Dispatcher.BeginInvoke(new Action(() => child.InvalidateVisual())));
             }));
-        }        
+        }
 
         public bool IsOpen
         {
@@ -512,6 +508,20 @@ internal void Close(object parameter)
             _closeDialogExecutionParameter = parameter;
         }
 
+        /// <summary>
+        /// Attempts to focus the content of a popup.
+        /// </summary>
+        /// <returns>The popup content.</returns>
+        internal UIElement FocusPopup()
+        {
+            var child = _popup?.Child;
+            if (child == null) return null;
+
+            child.Focus();
+            child.MoveFocus(new TraversalRequest(FocusNavigationDirection.Next));
+            return child;
+        }
+
         protected override void OnPreviewMouseDown(MouseButtonEventArgs e)
         {
             var window = Window.GetWindow(this);

MaterialDesignThemes.Wpf/DialogSession.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Windows.Threading;
 
 namespace MaterialDesignThemes.Wpf
 {
@@ -39,6 +40,7 @@ public void UpdateContent(object content)
 
             _owner.AssertTargetableContent();
             _owner.DialogContent = content;
+            _owner.Dispatcher.BeginInvoke(DispatcherPriority.Background, new Action(() => _owner.FocusPopup()));            
         }
 
         /// <summary>