anchor.diff:      function GetRectOfButton(AButton: TATTabButton): TRect;
       function GetRectOfButtonIndex(AIndex: integer; AtLeft: boolean): TRect;
       function GetScrollPageSize: integer;
  -    function IsTabVisible(AIndex: integer): boolean;
       procedure SetOptButtonLayout(const AValue: string);
       procedure SetOptVarWidth(AValue: boolean);
       procedure SetTabIndex(AIndex: integer);
  
positive.code:   Invalidate;
  end;
  
  procedure TATTabs.SwitchTab(ANext: boolean);
  begin
    if TabCount>1 then
      if ANext then
      begin
        if TabIndex=TabCount-1 then
          TabIndex:= 0
        else
          TabIndex:= TabIndex+1;
      end
      else
      begin
        if TabIndex=0 then
          TabIndex:= TabCount-1
        else
          TabIndex:= TabIndex-1;
      end;
  
negative.code:     procedure Clear;
      function DeleteTab(AIndex: integer; AAllowEvent, AWithCancelBtn: boolean): boolean;
      procedure MakeVisible(AIndex: integer);
      function IsTabVisible(AIndex: integer): boolean;
      procedure ShowTabMenu;
      procedure SwitchTab(ANext: boolean; ALoopAtEdge: boolean= true);
      procedure MoveTab(AFrom, ATo: integer; AActivateThen: boolean);
      procedure DoScrollLeft;
      procedure DoScrollRight;
  