Ad 3) Maybe good idea for sharing annotations made for the same document by different people. (But it would not be so simple to implement as it looks like. Exact location of text would have to be found by search. What if there already is annotation for that part of text. What if old and new annotations overlap...)
Ad 4) You may switch on/off display of sketches (at least in old pdf). If you wand to ged rid of sketches just move the file to another folder, but you will loose also annotations....
Generally, it might be cool feature to allow import/add of annotations/sketches/.... from different user (with his identification, so that it is possible to find who did it).
But, first let Onyx finish current version. When everything will work flawlessly we may ask new features.
