function GetButtonFromButtonStr(const AButtonStr: string): TImageEnViewButton;
var
  bt: TImageEnViewButton;
begin
  for bt := Low(TImageEnViewButton) to High(TImageEnViewButton) do
  begin
    if SameText(AButtonStr, ButtonToStr(bt)) then
    begin
      Result := bt;
      BREAK;
    end;
  end;
end;

ImageEnViewToolbar1.Buttons := ImageEnViewToolbar1.Buttons + [ButtonFromButtonString(ivbImageSave)];

function TformMain.GetButtonFromButtonStr(const AButtonStr: string): TImageEnViewButton;
var
  //bt: TImageEnViewButton;
  idx: Integer;
begin
  idx := UToolbarButtonStrings.SLToolbarButtonStrings.IndexOf(AButtonStr);
  Result := TImageEnViewButton(idx);

  (*for bt := Low(TImageEnViewButton) to High(TImageEnViewButton) do
  begin
    if SameText(AButtonStr, ButtonToStr(bt)) then
    begin
      Result := bt;
      BREAK;
    end;
  end;*)
end;