uses registry;

 

.....

 

procedure TForm1.Button1Click(Sender: TObject);

var

  Reg:TRegistry;

  KeyName: String;

  ValueStr: String;

begin

  Reg:=TRegistry.Create;

  try

    Reg.RootKey:=HKEY_CLASSES_ROOT;

    KeyName:='htmlfileshellopencommand';

    if Reg.OpenKey(KeyName, False) then

    begin

      ValueStr:=Reg.ReadString('');

      Reg.CloseKey;

      Label1.Caption:=ValueStr;

    end

    else

      ShowMessage('No default webbrowser !');

  finally

    Reg.Free;

  end;

end;