fix(dock): centralize tear-off logic and ensure transactional integrity

src/Editor/Ghost.Editor/App.xaml.cs

@@ -53,6 +53,16 @@ public partial class App : Application
         }
     }
 
+    /// <summary>
+    /// Creates, registers, and shows a new DockWindow for a torn-off tab.
+    /// </summary>
+    internal static void CreateAndShowDockWindow(object tabContent)
+    {
+        var newWindow = new Ghost.Editor.View.Windows.DockWindow(tabContent);
+        AddSecondaryWindow(newWindow);
+        newWindow.Activate();
+    }
+
     internal IHost Host
     {
         get;

src/Editor/Ghost.Editor/View/Controls/DockLayout.cs

@@ -299,15 +299,26 @@ public sealed partial class DockLayout : Control
 
     private void TabView_TabDroppedOutside(Microsoft.UI.Xaml.Controls.TabView sender, Microsoft.UI.Xaml.Controls.TabViewTabDroppedOutsideEventArgs args)
     {
-        if (_sourceNode != null && _draggedItem != null && TabTornOff != null)
+        if (_sourceNode != null && _draggedItem != null)
         {
+            if (TabTornOff == null)
+            {
+                Logger.LogWarning("Tab dropped outside but no TabTornOff subscribers found.");
+                ClearDragOperationState();
+                return;
+            }
+
             int originalIndex = _sourceNode.Items.IndexOf(_draggedItem);
+            object? originalSelection = _sourceNode.SelectedItem;
+
             if (originalIndex == -1)
             {
                 ClearDragOperationState();
                 return;
             }
 
+            try
+            {
                 // Remove from current tree
                 if (_sourceNode.Items.Remove(_draggedItem))
                 {
@@ -323,14 +334,17 @@ public sealed partial class DockLayout : Control
                     {
                         // Rollback: Re-insert the item at original position if the tear-off handler fails
                         _sourceNode.Items.Insert(originalIndex, _draggedItem);
-                    _sourceNode.SelectedItem = _draggedItem;
+                        _sourceNode.SelectedItem = originalSelection;
                         Logger.LogError(ex);
                     }
                 }
-
+            }
+            finally
+            {
                 ClearDragOperationState();
             }
         }
+    }
 
     private object? _draggedItem;
     private DockPanelNode? _sourceNode;

src/Editor/Ghost.Editor/View/Windows/DockWindow.xaml.cs

@@ -22,8 +22,6 @@ internal sealed partial class DockWindow : WindowEx
 
     private void OnTabTornOff(object? sender, TabTornOffEventArgs e)
     {
-        var newWindow = new DockWindow(e.TabContent);
+        App.CreateAndShowDockWindow(e.TabContent);
-        App.AddSecondaryWindow(newWindow);
-        newWindow.Activate();
     }
 }

src/Editor/Ghost.Editor/View/Windows/EngineEditorWindow.xaml.cs

@@ -1,3 +1,4 @@
+using Ghost.Core;
 using Ghost.Editor.Core;
 using Ghost.Editor.Core.Contracts;
 using Ghost.Editor.Core.Services;
@@ -41,12 +42,30 @@ internal sealed partial class EngineEditorWindow : WindowEx
     {
         // For static tabs in EngineEditorWindow, we remove the item from TabItems
         if (sender.TabItems.Contains(args.Item))
+        {
+            int originalIndex = sender.TabItems.IndexOf(args.Item);
+            object? originalSelection = sender.SelectedItem;
+
+            try
             {
                 sender.TabItems.Remove(args.Item);
                 
-            var newWindow = new DockWindow(args.Item);
+                try
-            App.AddSecondaryWindow(newWindow);
+                {
-            newWindow.Activate();
+                    App.CreateAndShowDockWindow(args.Item);
+                }
+                catch (Exception ex)
+                {
+                    // Rollback: Re-insert the item at original position if the tear-off fails
+                    sender.TabItems.Insert(originalIndex, args.Item);
+                    sender.SelectedItem = originalSelection;
+                    Logger.LogError(ex);
+                }
+            }
+            catch (Exception ex)
+            {
+                Logger.LogError(ex);
+            }
         }
     }