Roundup's web UI makes it very easy to unlink a message or file from an issue, with a nice big 'remove' button next to each one.  Any user can do this with one click, yet I don't see an easy way to reverse the operation.  The only ways I have found so far to re-link a message are to log in to the host server and run a roundup-admin command, or contrive a custom URL using detailed knowledge from the customization docs.  This makes it a hassle to deal with accidental or inappropriate removals.

I'd like to see a relink or restore command on the web UI, for symmetry with the remove button.

I tried adding this myself, but the only place I found that knew where a message had been unlinked from was the item history, which is not displayed using a template.  Consequently, I had to hack up the templating.py code, imposing my change on all trackers.  I wasn't satisfied with the result.