Delphi 11.3: save MHT with resources without dialog

Question

My code:

uses
  System.SysUtils, MSHTML, ActiveX, SHDocVw;

implementation

procedure TForm1.FormCreate(Sender: TObject);
begin
  WebBrowser1.Navigate('google.com');
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  Dispatch: IDispatch;
  OleCommand: IOleCommandTarget;
  vaIn, vaOut: OleVariant;
  FilePath: WideString;
begin
  Dispatch := (WebBrowser1.Document as IHTMLDocument2) as IDispatch;

  if Succeeded(Dispatch.QueryInterface(IOleCommandTarget, OleCommand)) then
  begin
    FilePath := ExtractFilePath(ParamStr(0)) + 'google.mht'; // Путь для сохранения MHT файла

    vaIn := FilePath;
    vaOut := OleVariant(True); // Передаем True для перезаписи файла, если он уже существует

    OleCommand.Exec(nil, OLECMDID_SAVEAS, OLECMDEXECOPT_PROMPTUSER, vaIn, vaOut);
  end;
end;

When you click the button, a dialog box for saving the web page opens. I need to save web page with resources in MHT without dialog boxes.

• I tried this:

command OLECMDID_	option OLECMDEXECOPT_	dialog box hidden?	saves MHT?
_SAVEAS	_DONTPROMPTUSER	❌ appears	❌ only HTML
_SAVEAS	_PROMPTUSER	❌ appears	✅ yes
_SAVEAS	_DODEFAULT	❌ appears	✅ yes
_SAVE	_DONTPROMPTUSER	✅	❌ don't save at all
_SAVE	_PROMPTUSER	✅	❌ don't save at all
_SAVE	_DODEFAULT	✅	❌ don't save at all

• I tried to use execWB like this:

  WB := (WebBrowser1.DefaultInterface as IWebBrowser2);
  WB.ExecWB(OLECMDID_SAVEAS, OLECMDEXECOPT_DONTPROMPTUSER, vaIn, vaOut);
  

  Dialog box also appears and what's most important it saves only html/htm and txt, no MHT.

• Default path in dialog box is always the path where the file was last saved, not FilePath's content.

What do I wrong? How to save a web page in FilePath as MHT format without showing a dialog box? Complete project on GitHub.