Selecting a new LayoutAnchorableTabPanel from an auto sized width panel, will no longer undock the LayoutAnchorableTabPanel.

Author: Dirkster99

source/Components/Xceed.Wpf.AvalonDock/Controls/LayoutAnchorableTabItem.cs

@@ -28,6 +28,7 @@ public class LayoutAnchorableTabItem : Control
 
     private bool _isMouseDown = false;
     private static LayoutAnchorableTabItem _draggingItem = null;
+    private static bool _cancelMouseLeave = false;
 
     #endregion
 
@@ -146,6 +147,10 @@ protected override void OnMouseMove( System.Windows.Input.MouseEventArgs e )
         _isMouseDown = false;
         _draggingItem = null;
       }
+      else
+      {
+        _cancelMouseLeave = false;
+      }
     }
 
     protected override void OnMouseLeftButtonUp( System.Windows.Input.MouseButtonEventArgs e )
@@ -163,10 +168,13 @@ protected override void OnMouseLeave( System.Windows.Input.MouseEventArgs e )
 
       if( _isMouseDown && e.LeftButton == MouseButtonState.Pressed )
       {
-        _draggingItem = this;
+        // drag the item if the mouse leave is not canceled.
+        // Mouse leave should be canceled when selecting a new tab to prevent automatic undock when Panel size is Auto.
+        _draggingItem = !_cancelMouseLeave ? this : null;
       }
 
       _isMouseDown = false;
+      _cancelMouseLeave = false;
     }
 
     protected override void OnMouseEnter( MouseEventArgs e )
@@ -215,6 +223,11 @@ internal static void ResetDraggingItem()
       _draggingItem = null;
     }
 
+    internal static void CancelMouseLeave()
+    {
+      _cancelMouseLeave = true;
+    }
+
     #endregion
   }
 }

source/Components/Xceed.Wpf.AvalonDock/Layout/LayoutContent.cs

@@ -22,7 +22,7 @@ This program is provided to you under the terms of the Microsoft Public
 using System.Globalization;
 using System.Windows.Media;
 using System.ComponentModel;
-
+using Xceed.Wpf.AvalonDock.Controls;
 
 namespace Xceed.Wpf.AvalonDock.Layout
 {
@@ -159,6 +159,7 @@ public bool IsSelected
             parentSelector.SelectedContentIndex = _isSelected ? parentSelector.IndexOf( this ) : -1;
           OnIsSelectedChanged( oldValue, value );
           RaisePropertyChanged( "IsSelected" );
+          LayoutAnchorableTabItem.CancelMouseLeave();
         }
       }
     }