> Does it sound sensible to add the same to `dired-next-dirline' and
> `dired-prev-dirline'?

Well, I think it is as sensible as adding it to dired-(next|previous)-line...

> (If so, I can do the push.)

Yep, I know. Sorry.

If you do, please write the commit log in a more "ChangeLog"ish style (I mean, add the file name, etc.). TIA.