Add a toggle button to show all or only unread items
Add a button to all feeds to toggle view of all items or only unread (near the "Mark as read", "Refresh" and "Layout" buttons.)
Currently you need to open the "More options" menu and toggle an item. This will turn it into a single click.
Don G. commented
Yes! The "unread only" checkbox should be brought to the front!
I'd replace the mark as read combo button with an "unread only" checkbox.
But there's enough space for more buttons - you can move more items from the options button (...) to the toolbar.
If you're in a mode to show only unread subjects, and you enter a fully read feed, you see it empty.
In this case, it would be nice to see all the unread threads instead of the empty feed.
This can be optional.