procedure TOpenDialog.CanClose(var CanClose: Boolean);
    var
      I: Integer;
    {$IFDEF MSWINDOWS}
      Drive: string;
      DT: Cardinal;
    {$ENDIF}
    begin
      if Form <> nil then
        (Form as IFileDialogForm).ListFiles(FFiles);
      if FFiles.Count > 0 then
      begin
        FFilename := FFiles[0];
    {$IFDEF MSWINDOWS}

    {$ifdef JGO}
        if (Length(FFilename) > 2)
        and (FFilename[2] = DriveDelim)
        and (FFilename[3] = '\') then
        begin
          Drive := Copy(FFilename, 1, 3);
    {$else}
        if (Length(FFilename) > 1) and (FFilename[2] = DriveDelim) then
        begin
          Drive := Copy(FFilename, 1, 2);
    {$endif}
          DT := Windows.GetDriveType(PChar(Drive));
          CanClose := (DT <> DRIVE_UNKNOWN) and (DT <> DRIVE_NO_ROOT_DIR);
          ...