Sorry – my mistake. I thought that Browser Console shows me all events since FF was started. Now I realize that it only tells me events that occur when the Console is open.
I disabled Brief, exited FF, restarted FF, opened Browser Console, and enabled Brief. At that point, it shows me
Brief: opening database in persistent storage database.js:43
I then click on the Brief icon. The Brief window opens, and that message appears in Console a second time.
I click on every word in the window – Options, Organize, Refresh, All Items, etc - and nothing happens, and no Console messages appear.
I go to Add-Ons Manager and open the Brief options there, and change an option. I get the same message a third time, plus:
Brief: update pref feedview.sortUnreadViewOldestFirst to false prefs.js:30
Every time I open the Brief window I get the “persistent storage” message, but nothing changes.