All styles being stripped out

Hi,

We found an issue where the preg_match was working on our php-5.5 server, but not on our php 5.3 server. This meant that in the function _ckeditor_filter_styles_regex_builder() there would be no matches for preg_match and so the last line $e->removeAttribute('style') would be called and would strip out all the styles.

Pretty much by trial and error we found it to be an issue with the "?" in the regex. Escaping all but one of the question marks seems to fix the problem in php-5.3 and php-5.5 still seems to work with the escaping.

Index: ckeditor_filter.module
===================================================================
--- ckeditor_filter.module      (revision 269)
+++ ckeditor_filter.module      (working copy)
@@ -76,13 +76,13 @@
  */
 function _ckeditor_filter_styles_regex_builder($styles) {
   if(!empty($styles)) {
-    $regex = '/(?:';
+    $regex = '/(\?:';
     foreach($styles as $style) {
-      $regex .= '(?!(?:|[^$]*[;\s])' . $style . '\s*:[^$;]*)';
+      $regex .= '(\?!(\?:|[^$]*[;\s])' . $style . '\s*:[^$;]*)';
     }
     $regex .= '[^$]*$|';
     foreach($styles as $style) {
-      $regex .= '(?=(?:|[^$]*[;\s])(' . $style . '\s*:[^$;]*))?';
+      $regex .= '(\?=(\?:|[^$]*[;\s])(' . $style . '\s*:[^$;]*))?';
     }
     return $regex . '[^$]*$)/i';
   }

I am couldn't find anything in the change notes for PHP as to why the unescaped regex works on php-5.5 and not php-5.3, but thought this might be useful for anyone running a Centos / RHEL 6 installation with php 5.3