I have a tiny graphic design idea. Not at all an important issue, but it would be nice.
When I’m viewing unread stories only, the list of my feeds gets smaller and smaller, which is a nice indicator of how much is left. Until I read the last one. I expect that space to close, or show just a blank row. Instead, the space they were in blows up to a box big enough for 10 feeds, just for a globe and to say ‘You have no unread stories.’
I get that an indicator is necessary, so you don’t have people panicking when it looks like their feeds are gone. I suggest moving it down to the bottom of the sidebar, like so: 
Oh, and thank you for Newsblur!