I think it's currently not possible to make public (or private) all of our bookmarks for a specific tag in one operation, we have to edit each bookmark one by one.
As I imported many bookmarks and off course by default everything appeared as private, I thought it would have been useful to be able to select a tag and make every bookmark public for this specific tag. Also it could be useful to be able to do more operations for bookmarks which have a specific tag, like being able to delete them.
