In the old version of BRN, there was an option (right clicking in the tree?) that enabled processing the entire file name including extension.
(The default was off, IIRC, but the option stayed set over multiple invocations).
This option is missing from the current version. (3.0.0.1)
If you bring it back, then things like Case(4), Remove(5), Add(7), etc. can be used to operate on file extensions, not to mention vanilla Replace(3).
Several users have posted questions along the lines of "How do I rename file extensions" and received multiple step answers. They are complicated, not obvious for casual users, and not mentioned at all in the help.
So how about bringing it back? (Put it in the Menu Bar "Renaming Options" drop down.)
If nothing else, please add an "Include Ext." check box on Replace(3), just like appears on RegEx(1).
Thanks!