Get Active Window Caption

function ActiveCaption: string;

var

  Handle: THandle;

  Len: LongInt;

  Title: string;

begin

  Result := '';

  Handle := GetForegroundWindow;

  if Handle <> 0 then

  begin

    Len := GetWindowTextLength(Handle) + 1;

    SetLength(Title, Len);

    GetWindowText(Handle, PChar(Title), Len);

    ActiveCaption := TrimRight(Title);

  end;

end;