Just played around with that myself. Changing the resolution to 1280x720 for main window and UI fixes this for me.
Edit: Yes, I did make sure to use the main menu plugin you were using.
Edit Edit: Just tested it with the UI resolution by default, and I am 99% certain you have the UI resolution not equal to your Screen resolution, since the same exact thing you have in your screenshot is what happens when I keep the UI resolution smaller than the screen.
