fix(dock): address reviewer feedback on window tear-off

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

@@ -23,6 +23,7 @@ namespace Ghost.Editor;
 public partial class App : Application
 {
     private Window? _window;
+    private readonly List<Window> _secondaryWindows = new();
 
     internal static Window? Window
     {
@@ -39,6 +40,15 @@ public partial class App : Application
         }
     }
 
+    internal static void AddSecondaryWindow(Window window)
+    {
+        if (Current is App app)
+        {
+            app._secondaryWindows.Add(window);
+            window.Closed += (s, e) => app._secondaryWindows.Remove(window);
+        }
+    }
+
     internal IHost Host
     {
         get;

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

@@ -300,12 +300,15 @@ public sealed partial class DockLayout : Control
         if (_sourceNode != null && _draggedItem != null)
         {
             // Remove from current tree
-            _sourceNode.Items.Remove(_draggedItem);
+            if (_sourceNode.Items.Remove(_draggedItem))
-            DockMutationEngine.CleanupEmptyNodes(_sourceNode, Root);
+            {
+                DockMutationEngine.CleanupEmptyNodes(_sourceNode);
 
-            // Create new window
+                // Create new window and register it with App to prevent GC
-            var newWindow = new Ghost.Editor.View.Windows.DockWindow(_draggedItem);
+                var newWindow = new Ghost.Editor.View.Windows.DockWindow(_draggedItem);
-            newWindow.Activate();
+                App.AddSecondaryWindow(newWindow);
+                newWindow.Activate();
+            }
 
             ClearDragOperationState();
         }

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

@@ -3,7 +3,7 @@ using WinUIEx;
 
 namespace Ghost.Editor.View.Windows;
 
-public sealed partial class DockWindow : WindowEx
+internal sealed partial class DockWindow : WindowEx
 {
     public DockWindow(object initialTabContent)
     {
@@ -16,7 +16,5 @@ public sealed partial class DockWindow : WindowEx
         rootGroup.AddChild(panel);
         
         PART_DockLayout.Root = rootGroup;
-        
-        // Optional: Titlebar setup etc.
     }
 }