anchor.diff:    TControl2 = class(TControl);
   
   procedure TATTabs.MouseMove(Shift: TShiftState; X, Y: integer);
  +var
  +  IsX: boolean;
   begin
     inherited;
  -  FTabIndexOver:= GetTabAt(X, Y);
  +  FTabIndexOver:= GetTabAt(X, Y, IsX);
     FTabIndexDrop:= FTabIndexOver;
   
     if Assigned(FOnTabOver) then
  
positive.code:   FMouseDownButton:= Button;
    FMouseDownShift:= Shift;
  
    FTabIndexOver:= GetTabAt(X, Y);
    SetTabIndex(FTabIndexOver);
  
    Invalidate;
  end;
  
negative.code: 
  procedure TATTabs.MouseDown(Button: TMouseButton; Shift: TShiftState;
    X, Y: integer);
  var
    IsX: boolean;
  begin
    FMouseDown:= Button in [mbLeft, mbMiddle]; //but not mbRight
    FMouseDownRightBtn:= (Button = mbRight);
  