Consider the following testcase (XHTML, but an equivalent DOM can be
constructed in HTML, of course).
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml";>
<body>
aaa
<optgroup>
bbb
</optgroup>
ccc
<option>
ddd
</option>
eee
</body>
</html>
I observe the following behaviors:
1) Gecko makes optgroup and option blocks (and applies some
bold/italic/font-size styles to the optgroup, at least).
2) Presto renders the text in the <optgroup> (which it treats as an
inline) but doesn't render the <option> at all.
3) Webkit renders neither the <optgroup> nor the <option>
4) Trident (IE8/9) renders like Gecko as far as styling the optgroup,
except it makes the optgroup and option inlines, not blocks.
I have a hard time believing any of this matters for interop, but....
-Boris
