From ece04af23ed04a5ad4d8f2277e96bc7c41042b2c Mon Sep 17 00:00:00 2001
From: Dirkster99 <Dirk.Bahle@gmx.de>
Date: Mon, 12 Nov 2018 20:02:41 +0100
Subject: [PATCH] Fix for issue #9

https://github.com/xceedsoftware/wpftoolkit/issues/1403
https://github.com/xceedsoftware/wpftoolkit/issues/1119
---
 .../Xceed.Wpf.AvalonDock/Layout/Extentions.cs | 53 +++++++++++--------
 1 file changed, 30 insertions(+), 23 deletions(-)

diff --git a/source/Components/Xceed.Wpf.AvalonDock/Layout/Extentions.cs b/source/Components/Xceed.Wpf.AvalonDock/Layout/Extentions.cs
index 4f319e1b..09c3469a 100644
--- a/source/Components/Xceed.Wpf.AvalonDock/Layout/Extentions.cs
+++ b/source/Components/Xceed.Wpf.AvalonDock/Layout/Extentions.cs
@@ -85,34 +85,41 @@ public static bool IsOfType<T, S>( this ILayoutContainer container )
       return container is T || container is S;
     }
 
-    public static AnchorSide GetSide( this ILayoutElement element )
-    {
-      var parentContainer = element.Parent as ILayoutOrientableGroup;
-      if( parentContainer != null )
-      {
-        var layoutPanel = parentContainer as LayoutPanel;
-        if( layoutPanel == null )
+        public static AnchorSide GetSide(this ILayoutElement element)
         {
-          layoutPanel = parentContainer.FindParent<LayoutPanel>();
+            var parentContainer = element.Parent as ILayoutOrientableGroup;
+            if (parentContainer != null)
+            {
+                if (!parentContainer.ContainsChildOfType<LayoutDocumentPaneGroup, LayoutDocumentPane>())
+                    return GetSide(parentContainer);
+
+                foreach (var childElement in parentContainer.Children)
+                {
+                    if (childElement == element ||
+                        childElement.Descendents().Contains(element))
+                        return parentContainer.Orientation == System.Windows.Controls.Orientation.Horizontal ?
+                            AnchorSide.Left : AnchorSide.Top;
+
+                    var childElementAsContainer = childElement as ILayoutContainer;
+                    if (childElementAsContainer != null &&
+                        (childElementAsContainer.IsOfType<LayoutDocumentPane, LayoutDocumentPaneGroup>() ||
+                         childElementAsContainer.ContainsChildOfType<LayoutDocumentPane, LayoutDocumentPaneGroup>()))
+                    {
+                        return parentContainer.Orientation == System.Windows.Controls.Orientation.Horizontal ?
+                            AnchorSide.Right : AnchorSide.Bottom;
+                    }
+                }
+            }
+
+            Debug.Fail("Unable to find the side for an element, possible layout problem!");
+            return AnchorSide.Right;
         }
 
-        if( (layoutPanel != null) && ( layoutPanel.Children.Count > 0 ) )
-        {
-          if( layoutPanel.Orientation == System.Windows.Controls.Orientation.Horizontal )
-            return layoutPanel.Children[ 0 ].Descendents().Contains( element ) ? AnchorSide.Left : AnchorSide.Right;
-          return layoutPanel.Children[ 0 ].Descendents().Contains( element ) ? AnchorSide.Top : AnchorSide.Bottom;
-        }
-      }
-
-      Debug.Fail( "Unable to find the side for an element, possible layout problem!" );
-      return AnchorSide.Right;
-    }
-
-    #endregion
+        #endregion
 
-    #region Internal Methods
+        #region Internal Methods
 
-    internal static void KeepInsideNearestMonitor( this ILayoutElementForFloatingWindow paneInsideFloatingWindow )
+        internal static void KeepInsideNearestMonitor( this ILayoutElementForFloatingWindow paneInsideFloatingWindow )
     {
       Win32Helper.RECT r = new Win32Helper.RECT();
       r.Left = ( int )paneInsideFloatingWindow.FloatingLeft;