procedure TForm1.Button2Click(Sender: TObject);
var
  WinIni : TIniFile;
  WinDir :PChar;
 s : array[0..64] of char;
begin
 WinDir:=PChar(GetWinDir);
 StrCat(WinDir, '\win.ini');
  WinIni := TIniFile.Create(WinDir);
  WinIni.WriteString('Extensions',
         'bor',
         'C:\PROGRA~1\BORLAND\DELPHI~1\PROJECT1.EXE ^.bor');
  WinIni.Free;
  StrCopy(S, 'Extensions');
  SendMessage(HWND_BROADCAST, WM_WININICHANGE,
       0, LongInt(@S));
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  reg: TRegistry;
begin
  reg := TRegistry.Create;
  reg.RootKey := HKEY_CLASSES_ROOT;
  reg.LazyWrite := false;
 {Add Program Support}
  reg.OpenKey('.bor\shell\open\command', true);
{Invoke the program passing the file name as the first parameter}
  reg.WriteString('','C:\Program Files\Borland\Delphi 3\Project1.exe %1');
 {Add Icon Display}
  reg.CloseKey;
  reg.OpenKey('.bor\DefaultIcon', true);
{Use the first icon in the executable to display}
  reg.WriteString('','C:\Program Files\Borland\Delphi 3\Project1.exe,0');
  reg.CloseKey;
  reg.free;
end;