Unselect some documents from a results listing

As a Web UI user, I want to unselect some documents

AC
Once I select all documents, I can unselect documents manually one by one.
All documents except the ones explicitly unselected are considered as part of the selection.

e.g. in a folderish doc listing 100 documents, 50 documents are visible.
Select all, unselect doc A manually:

• the UI shows a total of 99 selected results, broken down as following:
  • doc A is not selected in the UI, and not counted in the selected results
  • the other 49 visible documents are selected in the UI and counted in the selected results
  • the 50 non visible documents are counted in the selected results