When a user edits (with m_edit) the first post of a topic which currently has a topic type that the user isn't allowed to create (e.g. topic is currently announcement but user can only create normal and sticky topics), then the option to "change topic type to: normal" is always preselected. Since there is no warning either, the user will silently change the topic to a normal one.
IMO one of the following should happen instead:
- add an additional option "don't change topic type" (or just add the current type to the list of options, imho the best solution)
- display a message "warning: this topic is of type XXX but you are not allowed to create such topics. If you click save, the topic will be converted to type YYY"
- disallow editing the first post ("if you're not allowed to create it, then you're not allowed to edit it either")