We provide preview support when editing main textual body of an artifact (ticket details, wiki content, etc.), but not when editing comments to an artifacts. Apparently, for consistency, we should allow to do that, otherwise we get markup underuse (because people are afraid to use it, not knowing if it'll come ok or no), or get broken markup.
Originally by: wladid
Please consider the same issue for forum. Create topic or Reply contains also no preview functionality.
Changes are on js/1769. To test, add comments to an artifact. Make sure add, edit, and reply forms have preview buttons. Also confirm there is a preview button on create topic: /p/test/discussion/create_topic/
Looks good, merging and closing.