[Plugin: Dean’s FCKEditor For WordPress] post-new.php broken in IE6

System:
Wordpress 2.7.0
FCKEditor for WordPress plugin (V2.5.0)
Disable Revisions and Autosave plugin

Browser: Internet Explorer 6 (yeah, I know, but I cannot control my users)

Problem:
Rich text editing (Wysiwig editing) in the user’s profile should be turned off.
If rich text editing is on, post-new.php results in an error:

In Dutch:
De website https://www.example.com/blog/wp-admin/post-new.php kan niet worden geopend.
De bewerking is afgesloten.

In English someting like this:
The website https://www.example.com/blog/wp-admin/post-new.php cannot be opened.
The operation was aborted.

Side effect: WordPress uses wp-admin/js/editor.js and cannot get the contents of the editingArea. Result: new posts will not be submitted.

Solution: ensure rich text editing is turned off (by documentation or by software).

Workaround:
Make some changes in wp-admin/admin-header.php:

# Enable TinyMCE only if Dean's FCKEditor for WordPress is not active
if ( !$deans_fckeditor && in_array( $pagenow, array('post.php', 'post-new.php',
	'page.php', 'page-new.php') ) ) {
		add_action( 'admin_head', 'wp_tiny_mce' );
}