I just downloaded a Foldingtext trial to try it out (Yosemite) but I have this weird glitch where there is text stuck to the bottom of the screen. I also witnessed it happening at other times (outside of todos) but I can’t remember how.
(apparently you need to click on the GIF before it plays the animation)
No plugins, it’s a raw install of the trial. I also didn’t mess around with any config, I just opened the Todo from the Help menu and completed one todo entry to test it out.