[Marco van Herwaarden]

Limiting BB-Codes to Usergroups is extremely difficult, and if done correct would add a lot of processing to parsing a post.

Think about the following:
- A BB-code to wich a user don't have permission, is like a non-existant bb-code, ie. just plain text. It should just turn up as plain text.
- BB-Codes are parsed when a post is first time shown (and again if not in post_parsed anymore). This means that parsing the post and evaluating the bb-codes might be done by a member who is in a different usergroup then the original poster. Retrieving the usergroup permissions of the poster might add a lot of processing.
- What if a Staff member edit the original post, and uses a bb-code that only a few usergroups have permission to? Are the permissions of the original poster used when parsing the post? The permissions of that Staff member (what if the original poster edits his post afterwards, can he then suddenly use staff bb-codes)?
..............

Probably 100 more caveats to think of.