Often I share OmniOutliner files with collaboration partners via a shared Dropbox folder. In doing so you have to be very careful not to have both people making changes at the same time. OmniOutliner hates that. It is not alone. A lot of apps don't appreciate multiple authors making changes at once. It can lead to data loss and, in extreme circumstances, the end of days.
So on my appearance on the CMD+Space podcast, I talked about my goofy way of sharing these types of files. I've received several requests for clarification so here goes.
First, create the shared Dropbox folder and move your file in.
Next, Create a new text file in TextEdit and save it to the shared folder. Name the file "File Log".
You can either leave the file blank or put in a running list of changes. I usually do the latter with a time/date stamp.
Whenever you want to open the working file (in this case an OmniOutliner file), put a red Label on the text file. This way, if your fellow collaborator stumbles into the folder to open the file, they can see a red label, telling them to stay out. It is like leaving a sock on the dorm room door. Well, sort of.
When you are done, update your change log in the File Log text file and then change the file label to green. If you and your collaboration partner use a little discipline you can collaborate without stepping on any toes.