Since we only get "one shot" when submitting a bug report, how difficult would it be to have a preview?
It appears (per the url mentioned in your comment 0) this was added to Bugzilla 5.x, and so will be available (possibly as a user preference) when we upgrade to that version. I'll create a dependent issue now.
Bugzilla has now been upgraded to version 5.x, which includes Preview for initial bug creation (Description) and adding Comments.
Please confirm this is what you were after, and we'll close this issue if you're satisfied