AnchorDocking fixes by Andrey Zubarev (approved by Željan).

Merge request !111

components/anchordocking/anchordocking.pas

@@ -489,6 +489,7 @@ type
     procedure StoreConstraints;
     function GetSitePreferredClientSize: TPoint;
     function IsEnabledControl(Control: TControl):Boolean; override;
+    function CanBeDoubleDocked:Boolean; override;
 
     property Site: TWinControl read FSite; // the associated TControl (a TAnchorDockHostSite or a custom dock site)
     property DockSite: TAnchorDockHostSite read FDockSite; // if Site is a TAnchorDockHostSite, this is it
@@ -4460,6 +4461,8 @@ begin
   OldControl:=GetOneControl;
   OldSite:=MakeSite(OldControl);
   AddCleanControl(OldSite);
+  if not(OldControl is TAnchorDockHostSite) then
+    OldSite.Header.FHeaderPosition:=Header.FHeaderPosition;
   OldSite.AnchorClient(0);
   // the LCL will compute the bounds later after EnableAutoSizing
   // but the bounds are needed now => set them manually
@@ -5184,6 +5187,7 @@ begin
 
     // header
     Header.Align:=Site.Header.Align;
+    Header.HeaderPosition:=Site.Header.HeaderPosition;
     Header.Caption:=Site.Header.Caption;
     UpdateHeaderShowing;
     Caption:=Site.Caption;
@@ -7560,6 +7564,11 @@ begin
   Result := (DockMaster <> nil) and DockMaster.IsSite(Control);
 end;
 
+function TAnchorDockManager.CanBeDoubleDocked:Boolean;
+begin
+  Result := False;
+end;
+
 { TAnchorDockSplitter }
 
 procedure TAnchorDockSplitter.SetResizeAnchor(const AValue: TAnchorKind);

lcl/controls.pp

@@ -624,6 +624,7 @@ type
     procedure SetReplacingControl(Control: TControl); virtual;
     function AutoFreeByControl: Boolean; virtual;
     function IsEnabledControl(Control: TControl):Boolean; virtual;
+    function CanBeDoubleDocked:Boolean; virtual;
   end;
 
   TDockManagerClass = class of TDockManager;
@@ -4638,6 +4639,11 @@ begin
 
 end;
 
+function TDockManager.CanBeDoubleDocked:Boolean;
+begin
+  result:=true;
+end;
+
 function TDockManager.IsEnabledControl(Control: TControl):Boolean;
 begin
   Result := true;

lcl/include/dragmanager.inc

@@ -367,6 +367,25 @@ procedure TDockPerformer.DragMove(APosition: TPoint);
     end;
   end;
 
+  function IsClientChildOfControl(AControl:TWinControl): Boolean;
+  var
+    Client:TControl;
+  begin
+    Result := False;
+    Client := FDockObject.Control;
+    if Assigned(AControl) then
+      while Assigned(Client) do
+      begin
+        if AControl=Client then
+        begin
+          Result := True;
+          exit;
+        end;
+        Client := Client.Parent;
+      end;
+  end;
+
+
   function FindDockSiteAtPosition: TWinControl;
   //Replace with lookup in Screen.Zorder(?)
   var
@@ -416,6 +435,9 @@ procedure TDockPerformer.DragMove(APosition: TPoint);
         if not AControl.IsVisible then continue;
         if AControl=FDockObject.Control then continue;
         if IsControlChildOfClient(AControl) then continue;
+        if AControl.DockManager<>nil then
+          if not AControl.DockManager.CanBeDoubleDocked then
+            if IsClientChildOfControl(AControl) then continue;
 
         if ItCanBeHostSite then
         begin