Change the default printer in Windows

Problem/Question/Abstract:

How can I change the default printer in Windows?

Answer:

If you want to change the the default printer in Windows OS, you must change the device key in the Windows section of the WIN.INI. After that you must send a WM_WININICHANGE message:

var
  strIni: array[0..MAX_PATH] of Char;
  arrWindows: array[0..64] of Char;
begin
  GetWindowsDirectory(strIni, SizeOf(strIni));
  StrCat(strIni, '\win.ini');
  with TIniFile.Create(strIni) do
  try
    WriteString('windows', 'device', 'HP LaserJet 4 Plus,HPPCL5MS,LPT1:');
  finally
    Free;
  end;

  StrCopy(arrWindows, 'windows');
  SendMessage(HWND_BROADCAST, WM_WININICHANGE, 0, LongInt(@arrWindows));
end;