=head2 GetWindowText($hwind)

Return text of $hwind, or undef on errors.

=cut
sub GetWindowText {
	my ($hwind) = @_;

	my $len = Win32::GUI::SendMessage($hwind, 0x000E, 0, 0) or return("");    #WM_GETTEXTLENGTH

	my $buf = " " x ($len + 1);
	my $addrBuf = unpack("L", pack('p', $buf));
	
	Win32::GUI::SendMessage($hwind, 0x000D, $len + 1, $addrBuf) or return(undef);    #WM_GETTEXT

	return( substr($buf, 0, $len) );
}