CSS Preview?

Hi,

I am currently using this code to change the css on the blogs on my mu system (http://pengchat.com)

<?php
/*
Plugin Name: Custom CSS
Plugin URI: http://rizapn.blogsome.com/
Description: A plug-in to add a Custom CSS capability to Wordpress MU. Custom CSS will "overwrite" a needed CSS value(s) from its original themes.
Author: Riza Purwo Nugroho
Version: 0.3b
Author URI: http://rizapn.blogsome.com/
*/

add_action('wp_head', 'custom_css_add_line');

function custom_css_add_line()
{
$base = get_option('fileupload_url');
$file = preg_replace('/.+?themes\//','',get_stylesheet_uri());
$file = str_replace('/','_',$file);
?><link rel="stylesheet" href="<?php echo $base; ?>/themes/<?php echo $file; ?>" type="text/css" media="screen" /><?php
}

add_action('admin_menu', 'custom_css_add_menu');

function custom_css_add_menu()
{
add_submenu_page('themes.php', 'Custom CSS', 'Custom CSS', 10, 'custom_css', 'custom_css_do_action');
}

function custom_css_do_action()
{
global $blog_id;

wp_admin_css('theme-editor');

$theme = get_current_theme();

$style_uri = get_stylesheet_uri();

$tfile = $_GET['tfile'];
if (empty($tfile)) $tfile = $_POST['tfile'];
if (empty($tfile)) $tfile = preg_replace('/^.+?themes\/(.+?)\/.+$/','$1',$style_uri);

$real_file = ABSPATH.get_option('upload_path')."/themes/${tfile}_".basename($style_uri);

if ($_POST['action']=='update')
{
$content = stripslashes($_POST['newcontent']);
if (!file_exists($real_file)) wp_mkdir_p(dirname($real_file));
if (empty($content)) {
if (file_exists($real_file)) {
unlink($real_file);
?><div class="error"><p><?php echo __('File deleted !'); ?></p></div><?php
}
}
else {
$f = fopen($real_file, 'w+');
if ($f !== FALSE) {
fwrite($f, $content);
fclose($f);
?><div id="message" class="updated fade"><p><?php _e("File edited successfully.") ?></p></div><?php
}
else { ?><div class="error"><p><?php echo __('Error processing your request.'); ?></p></div><?php }
}
}

elseif (file_exists($real_file)) {
$f = fopen($real_file, 'r');
$content = fread($f, filesize($real_file));
$content = htmlspecialchars($content);
}
if (empty($content))
$content = "/* Custom CSS - write your own CSS values to overwrite the ones from $theme */\n".
"\n";
?>

<div class="wrap">
<h2><?php _e('Edit Custom CSS'); ?></h2>

<form method="post" action="themes.php?page=custom_css">
<input type="hidden" name="action" value="update" />
<input type="hidden" name="tfile" value="<?php echo $tfile; ?>" />

<div class="tablenav">
<div class="alignleft"><big><?php echo basename($real_file); ?></big></div>
<br class="clear" />
</div>
<br class="clear" />
<div id="templateside">
<h3 id="bordertitle"><?php _e("Custom CSS Files"); ?></h3>

    <?php
    $dir = dirname($real_file);
    $num = 0;
    if (is_dir($dir) && ($d = opendir($dir)))
    while ($style_file = readdir($d))
    {
    $dfile = "$dir/$style_file";
    if (is_file($dfile) && preg_match('/(.+?)_style.css$/',$style_file,$MATCH))
    { print "
  • $style_file
  • \n"; $num++; }
    }
    if ($num<=0) print "
  • No file found !
  • \n";
    ?>

</div>

<div>
<textarea cols="80" rows="25" name="newcontent" id="newcontent" tabindex="1"><?php echo $content; ?></textarea>
</div>

<div>
<p class="submit">
<input type="submit" name="submit" value="<?php echo __('Update File'); ?>" tabindex="2" />
</p>
</div>
</form>

<div class="clear">   </div>
</div>
<?php
}
?>

Do you think this can be edited to add it so users can preview it?