One use of annotations is for reviewing draft versions of a document. In this scenario
a reviewer goes over the document and marks suggested changes. Then he sends
the document with the marked changes back to the author who incorporates them
into the document. Sometimes, there might be several people reviewing a document; 
in this case it is useful if they are able to 

  1) merge comments from the other reviewers (see bug #361292)
  2) comment on the other reviewer's suggestions
  3) mark changes to indicate whether they agree with them or not

The pdf format allows for this workflow via so called "revisions". Each annotation can
have several revisions (annotations with the IRT key set pointing to the original annotation).
These serve two purposes:

  -- lightweight comment threads (see point 2 above)
  -- indicating status of the annotation (accepted/rejected/...) (see point 3 above)

It would be nice if okular allowed for this workflow. Currently if a document has annotations
with revisions, the revisions are not even displayed (fine if they are only used for point 3, but
not even annotation status is displayed). Moreover okular does not allow for their creation.

I started working on implementing the workflow. Currently, the reviewboard request
here:

https://git.reviewboard.kde.org/r/127636/

implements at least displaying the revisions. The next step will be to allow creating revisions.
This will, however, need changes to poppler.



Reproducible: Always