Apply right to left mode after every layout build

src/ui/Features/Main/MainView.cs

@@ -100,6 +100,16 @@ protected override object Build()
             Dispatcher.UIThread.Post(() =>
             {
                 InitLayout.MakeLayout(this, _vm, Se.Settings.General.LayoutNumber);
+
+                // The window level right to left pass runs when the window opens,
+                // which is before this deferred layout build, so the freshly built
+                // grid and text boxes would stay left to right until the mode is
+                // toggled. Re-apply after building.
+                if (Se.Settings.Appearance.RightToLeft && TopLevel.GetTopLevel(this) is Window rtlWindow)
+                {
+                    MainHelpers.RightToLeftHelper.SetRightToLeftForDataGridAndText(rtlWindow);
+                }
+
                 _vm.ContentGrid.InvalidateMeasure();
                 _vm.ContentGrid.InvalidateArrange();
                 Dispatcher.UIThread.Post(() => _vm.SubtitleGrid.Focus());

src/ui/Features/Main/MainViewModel.cs

@@ -888,6 +888,12 @@ private void SetLayout(int layoutNumber)
         var idx = SubtitleGrid.SelectedIndex;
         var savedAudioTrack = _audioTrack;
         Se.Settings.General.LayoutNumber = InitLayout.MakeLayout(MainView!, this, layoutNumber);
+        if (Se.Settings.Appearance.RightToLeft && Window != null)
+        {
+            // The rebuilt layout starts left to right; re-apply the mode.
+            RightToLeftHelper.SetRightToLeftForDataGridAndText(Window);
+        }
+
         SelectAndScrollToRow(Math.Max(0, idx));
         Dispatcher.UIThread.Post(() => SubtitleGrid.Focus());
         RefreshSubtitlePreview();
@@ -5765,6 +5771,12 @@ private void VideoUndockControls()
             });
 
             InitLayout.MakeLayout12KeepVideo(MainView!, this);
+            if (Se.Settings.Appearance.RightToLeft && Window != null)
+            {
+                // The rebuilt layout starts left to right; re-apply the mode.
+                RightToLeftHelper.SetRightToLeftForDataGridAndText(Window);
+            }
+
             RefreshSubtitlePreview();
         });
     }