Regex to match image style in formatter name incorrect

The regex in the current version relies on the image style containing a-z, 0-9 and underscores. You can also include hyphens in the image style.

I fixed it (line 495) by switching the regex to:

if (preg_match('/^(.+)_fancybox$/', $display['type'], $matches)) {

You know this function will only be called by known styles, so it's relatively safe to just grab everything before _fancybox. I'm not even certain underscores are allowed in image styles, therefore we could possibly even switch to something simpler like strtok... This seems to work as an example:

echo strtok('screenshot-thumb_fancybox', '_');