Add a menu item to open unread in ThreadWatcher

src/Monitoring/ThreadWatcher.coffee

@@ -126,6 +126,11 @@ ThreadWatcher =
       for a in $$ 'a[title]', ThreadWatcher.list
         $.open a.href
       $.event 'CloseMenu'
+    openUnread: ->
+      return if $.hasClass @, 'disabled'
+      for a in $$ '.replies-unread a[title]', ThreadWatcher.list
+        $.open a.href
+      $.event 'CloseMenu'
     pruneDeads: ->
       return if $.hasClass @, 'disabled'
       for {siteID, boardID, threadID, data} in ThreadWatcher.getAll() when data.isDead
@@ -605,6 +610,14 @@ ThreadWatcher =
           @el.classList.toggle 'disabled', !ThreadWatcher.list.firstElementChild
           true
 
+      # `Open Unread` entry
+      entries.push
+        text: 'Open unread threads'
+        cb: ThreadWatcher.cb.openUnread
+        open: ->
+          @el.classList.toggle 'disabled', !$('.replies-unread', ThreadWatcher.list)
+          true
+
       # `Prune dead threads` entry
       entries.push
         text: 'Prune dead threads'