Fix ToolDock GripMode Inheritance on Split

src/Dock.Model/DockService.cs

@@ -17,6 +17,13 @@ private static void CopyDockGroup(IDockable source, IDockable target)
         }
     }
 
+    private static void CopyToolDockSettings(IToolDock source, IToolDock target)
+    {
+        target.IsExpanded = source.IsExpanded;
+        target.AutoHide = source.AutoHide;
+        target.GripMode = source.GripMode;
+    }
+
     private static bool IsValidMove(IDockable sourceDockable, IDock sourceDockableOwner, IDock targetDock, IDockable targetDockable)
     {
         if (targetDockable is IDock)
@@ -158,6 +165,14 @@ private void SplitToolDockable(IDockable sourceDockable, IDock sourceDockableOwn
         targetToolDock.Title = nameof(IToolDock);
         targetToolDock.Alignment = operation.ToAlignment();
         targetToolDock.VisibleDockables = factory.CreateList<IDockable>();
+        if (targetDock is IToolDock targetToolDockSource)
+        {
+            CopyToolDockSettings(targetToolDockSource, targetToolDock);
+        }
+        else if (sourceDockableOwner is IToolDock sourceToolDock)
+        {
+            CopyToolDockSettings(sourceToolDock, targetToolDock);
+        }
         CopyDockGroup(sourceDockable, targetToolDock);
 
         // Local split into a new (empty) dock: allow per Empty Dock Rule

tests/Dock.Model.UnitTests/ToolDockGripModeInheritanceTests.cs

@@ -0,0 +1,44 @@
+using Dock.Model;
+using Dock.Model.Avalonia;
+using Dock.Model.Avalonia.Controls;
+using Dock.Model.Controls;
+using Dock.Model.Core;
+using Xunit;
+
+namespace Dock.Model.UnitTests;
+
+public class ToolDockGripModeInheritanceTests
+{
+    [Fact]
+    public void SplitToolDockable_Inherits_GripMode_From_TargetDock()
+    {
+        var factory = new Factory();
+        var root = factory.CreateRootDock();
+        root.VisibleDockables = factory.CreateList<IDockable>();
+
+        var toolDock = new ToolDock
+        {
+            GripMode = GripMode.AutoHide,
+            VisibleDockables = factory.CreateList<IDockable>()
+        };
+
+        var tool1 = new Tool { Id = "Tool1", Title = "Tool1" };
+        var tool2 = new Tool { Id = "Tool2", Title = "Tool2" };
+
+        toolDock.VisibleDockables.Add(tool1);
+        toolDock.VisibleDockables.Add(tool2);
+        toolDock.ActiveDockable = tool1;
+        root.VisibleDockables.Add(toolDock);
+
+        factory.InitLayout(root);
+
+        var manager = new DockManager(new DockService());
+        var executed = manager.ValidateTool(tool2, toolDock, DragAction.Move, DockOperation.Right, bExecute: true);
+
+        Assert.True(executed);
+        var newDock = tool2.Owner as IToolDock;
+        Assert.NotNull(newDock);
+        Assert.NotSame(toolDock, newDock);
+        Assert.Equal(GripMode.AutoHide, newDock!.GripMode);
+    }
+}