[Andreas]

Try this hack (it's for RC2, might also work for earlier versions)

File functions_newpost.php

Before

PHP Code:

if ($post['preview'] OR sizeof($errors) > 0) 


Insert

PHP Code:

// PostSizeHack
// Make sure user does not user too large fonts
$pattern = "/\[size=[6-9]\].*\[\/size\]/si";            // Check for SIZE=6-9
$pattern2 = "/\[size=\+[5-9]\].*\[\/size\]/si";         // Check for SIZE=+5-9
$pattern3 = "/\[size=\+*[1-9][0-9]+\].*\[\/size\]/si";  // Check for SIZE=[+]10-xxxxx
if (preg_match($pattern, $post['message']) or
  preg_match($pattern2, $post['message']) or
  preg_match($pattern3, $post['message'])) {
  $post['preview'] = 1;
  eval('$errors[] = "Font size too large - max is 5";');
}
// PostSizeHack 


Colud be also made configurable via CP & phrased, but would make the hack a bit more "difficult"