function OpenSaveFileDialog(Parent: 
TWinControl; const DefExt, Filter, InitialDir, Title: string; var FileName: 
string; 
  MustExist, OverwritePrompt, NoChangeDir, DoOpen: Boolean): Boolean;
var
  ofn: TOpenFileName;
  szFile: array[0..MAX_PATH] of Char;
begin
  Result := False;
  FillChar(ofn, SizeOf(TOpenFileName), 0);
  with ofn do
  begin
    lStructSize := SizeOf(TOpenFileName);
    hwndOwner := Parent.Handle;
    lpstrFile := szFile;
    nMaxFile := SizeOf(szFile);
    if (Title <> '') then
      lpstrTitle := PChar(Title);
    if (InitialDir <> '') then
      lpstrInitialDir := PChar(InitialDir);
    StrPCopy(lpstrFile, FileName);
    lpstrFilter := PChar(ReplaceStr(Filter, '|', #0)+#0#0);
    if DefExt <> '' then
      lpstrDefExt := PChar(DefExt);
  end;

  if MustExist then
    ofn.Flags := ofn.Flags or OFN_FILEMUSTEXIST;

  if OverwritePrompt then
    ofn.Flags := ofn.Flags or OFN_OVERWRITEPROMPT;

  if NoChangeDir then
    ofn.Flags := ofn.Flags or OFN_NOCHANGEDIR;

  if DoOpen then
  begin
    if GetOpenFileName(ofn) then
    begin
      Result := True;
      FileName := StrPas(szFile);
    end;
  end
  else
  begin
    if GetSaveFileName(ofn) then
    begin
      Result := True;
      FileName := StrPas(szFile);
    end;
  end
end;