I'm fairly sure this has been a problem for a couple of years. This post is 5 months old, and certainly many people working at Evernote thought to themselves, while using Evernote on their 16:9 laptop displays, isn't there anything we can do about this?
Like just eliminate the entire pane and such display a Search field? You can literally select a different notebook 2" away. And the actions on the right margin could easily be menu items at the top. This is such a glaring UX issue that I can't believe it's existed this long.