diff --git a/examples/anchordocking/anchordocking.pas b/examples/anchordocking/anchordocking.pas
index 534ad7016c..2834b2ebdf 100644
--- a/examples/anchordocking/anchordocking.pas
+++ b/examples/anchordocking/anchordocking.pas
@@ -299,6 +299,7 @@ type
     property DockSite: TAnchorDockHostSite read FDockSite;
     property Site: TWinControl read FSite;
     property DockableSites: TAnchors read FDockableSites write FDockableSites;
+    function GetChildSite: TAnchorDockHostSite;
   end;
 
   { TAnchorDockMaster }
@@ -1092,19 +1093,37 @@ var
   Site: TAnchorDockHostSite;
   SavedSites: TFPList;
   LayoutNode: TAnchorDockLayoutTreeNode;
+  AForm: TCustomForm;
 begin
   SavedSites:=TFPList.Create;
   try
     for i:=0 to ControlCount-1 do begin
       AControl:=Controls[i];
       if not AControl.IsVisible then continue;
-      Site:=GetParentForm(AControl) as TAnchorDockHostSite;
-      if SavedSites.IndexOf(Site)>=0 then continue;
-      SavedSites.Add(Site);
-      debugln(['TAnchorDockMaster.SaveMainLayoutToTree Site=',DbgSName(Site)]);
-      DebugWriteChildAnchors(Site);
-      LayoutNode:=LayoutTree.NewNode(LayoutTree.Root);
-      Site.SaveLayout(LayoutTree,LayoutNode);
+      AForm:=GetParentForm(AControl);
+      if AForm=nil then continue;
+      if SavedSites.IndexOf(AForm)>=0 then continue;
+      SavedSites.Add(AForm);
+      debugln(['TAnchorDockMaster.SaveMainLayoutToTree AForm=',DbgSName(AForm)]);
+      DebugWriteChildAnchors(AForm);
+      if (AForm is TAnchorDockHostSite) then begin
+        Site:=TAnchorDockHostSite(AForm);
+        LayoutNode:=LayoutTree.NewNode(LayoutTree.Root);
+        Site.SaveLayout(LayoutTree,LayoutNode);
+      end else if (AForm.DockManager is TAnchorDockManager)
+      and (AForm.Parent=nil) then begin
+        // custom dock site
+        LayoutNode:=LayoutTree.NewNode(LayoutTree.Root);
+        LayoutNode.NodeType:=adltnCustomSite;
+        LayoutNode.Assign(AForm);
+        // can have one normal dock site
+        Site:=TAnchorDockManager(AForm.DockManager).GetChildSite;
+        if Site<>nil then begin
+          LayoutNode:=LayoutTree.NewNode(LayoutNode);
+          Site.SaveLayout(LayoutTree,LayoutNode);
+        end;
+      end else
+        raise EAnchorDockLayoutError.Create('invalid root control class '+DbgSName(AControl));
     end;
   finally
     SavedSites.Free;
@@ -3409,6 +3428,18 @@ begin
   Result:=true;
 end;
 
+function TAnchorDockManager.GetChildSite: TAnchorDockHostSite;
+var
+  i: Integer;
+begin
+  for i:=0 to Site.ControlCount-1 do
+    if Site.Controls[i] is TAnchorDockHostSite then begin
+      Result:=TAnchorDockHostSite(Site.Controls[i]);
+      exit;
+    end;
+  Result:=nil;
+end;
+
 { TAnchorDockSplitter }
 
 procedure TAnchorDockSplitter.SetResizeAnchor(const AValue: TAnchorKind);
diff --git a/examples/anchordocking/anchordockstorage.pas b/examples/anchordocking/anchordockstorage.pas
index f8aeed3a9a..6e4e8ba35d 100644
--- a/examples/anchordocking/anchordockstorage.pas
+++ b/examples/anchordocking/anchordockstorage.pas
@@ -47,7 +47,8 @@ type
     adltnControl,
     adltnSplitterHorizontal,
     adltnSplitterVertical,
-    adltnPages
+    adltnPages,
+    adltnCustomSite
     );
   TADLTreeNodeTypes = set of TADLTreeNodeType;
 
@@ -199,7 +200,8 @@ const
     'Control',
     'SplitterHorizontal',
     'SplitterVertical',
-    'Pages'
+    'Pages',
+    'CustomSite'
     );
   ADLWindowStateNames: array[TWindowState] of string = (
     'Normal',
@@ -964,7 +966,7 @@ var
 begin
   Name:=AControl.Name;
   BoundsRect:=AControl.BoundsRect;
-  if (AControl.Parent<>nil) and (AControl is TCustomForm) then begin
+  if (AControl.Parent=nil) and (AControl is TCustomForm) then begin
     WindowState:=TCustomForm(AControl).WindowState;
     Monitor:=TCustomForm(AControl).Monitor.MonitorNum;
   end else
@@ -1114,12 +1116,16 @@ begin
             dbgs(Side), '"', Anchors[Side], '"']));
     end;
   end;
-  // only the root node, pages and layouts can have children
-  if (Parent<>nil) and (Count>0) and (not (NodeType in [adltnLayout,adltnPages]))
+  // only the root node, pages, layouts and customsite can have children
+  if (Parent<>nil) and (Count>0)
+  and (not (NodeType in [adltnLayout,adltnPages,adltnCustomSite]))
   then
     raise EAnchorDockLayoutError.Create(
       Format(adrsNoChildrenAllowedForNodeType, ['"', Name, '"',
         ADLTreeNodeTypeNames[NodeType]]));
+  if (NodeType=adltnCustomSite) and (Count>1) then
+    raise EAnchorDockLayoutError.Create(Format(
+      adrsCustomDockSiteCanHaveOnlyOneSite, ['"', Name, '"']));
 
   // check grandchild
   for i:=0 to Count-1 do begin
@@ -1153,6 +1159,8 @@ begin
       // delete all children
       while ChildNode.Count>0 do
         ChildNode[0].Free;
+    end else if ChildNode.NodeType=adltnCustomSite then begin
+      // custom dock site
     end else if ChildNode.Count=0 then begin
       // inner node without child => delete
       DeleteNode(ChildNode);
diff --git a/examples/anchordocking/anchordockstr.pas b/examples/anchordocking/anchordockstr.pas
index 973f3b1080..f9da7362c6 100644
--- a/examples/anchordocking/anchordockstr.pas
+++ b/examples/anchordocking/anchordockstr.pas
@@ -63,6 +63,8 @@ resourcestring
     +'splitter: Node=%s%s%s Anchors[%s]=%s%s%s';
   adrsNoChildrenAllowedForNodeType = 'No children allowed for Node=%s%s%s '
     +'Type=%s';
+  adrsCustomDockSiteCanHaveOnlyOneSite = 'Custom dock site %s%s%s can have '
+    +'only one site.';
   adrsEmptyName = 'Empty name: ';
   adrsDuplicateName = 'Duplicate name: ';