WordPress/wp-admin/profile-update.php

<?php

require_once('admin.php');

check_admin_referer('update-profile' . $user_ID);

if ( !$_POST )
	die( __('No post?') );

$errors = edit_user($user_ID);

if (count($errors) != 0) {
	foreach ($errors as $id => $error) {
		echo $error . '<br/>';
	}
	exit;
}

if ( !isset( $_POST['rich_editing'] ) )
	$_POST['rich_editing'] = 'false';
update_user_option( $current_user->id, 'rich_editing', $_POST['rich_editing'], true );

do_action('personal_options_update');

if ( 'profile' == $_POST['from'] )
	$to = 'profile.php?updated=true';
else
	$to = 'profile.php?updated=true';

wp_redirect( $to );
exit;

?>