The User Interface is great, one of the best I've seen to-date, but the Accessibility Options, and the settings menu design, can be a hassle when you're in a pinch or first getting to know this app.

The Settings Menu's 'Window Size' not taking up the Full–Width of the window's real estate area, + the Menu's available Text being so small, makes your app not very user-friendly.

The Menu Settings Button ought to display an "X" when the settings menu is open so that users understand how to actually close this menu.

It's a no brainer, because, it's just common courtesy for people who really need those Accessibility Options, and Accessibility Options are a must!