Thank you for your reply, I was able to eliminate the falling note guides.
I don't want to see through Synthesia to the desktop, just display a background image. However, when I import a background image it is obscured by a colored overlay which I am not able to disable. Here is the image I am trying to place behind the notes:
As you can see, I'm losing some of my contrast due to the overlay layer, "screenBackground" in colors.xml
Anyway, the purpose of the overlay is to use Synthesia in concert with Ut Piano, and alternative notations system that uses a similarly colored staff. You can see examples of sheet music at utpiano.com