problem with opera 7 form submiting multibyte

the form is made by document.write

[Xuefer]

(it's key to use document.write to reproduce this problem)

var w = window.open("");
w.document.write('<form action="test.php"><textarea name="a"></textarea><input type="submit"></form>');

in test.php:
echo $_POST['a'];
echo ord($_POST['a']);

i get every multibyte chars replaced into '?' and 63 (ascii code)

how can i solve this problem

[jatar_k]

You can't see anything funny when you view source on the html page?

[Xuefer]

view source works in IE
blank in mozilla
and no response in opera 7