I'm guessing the fixed 900x900 window size is a bit big for your screen?
That's the funny thing: my screen res is 1360x768 so, even taking in account the taskbar, there is plenty of space for it to fit. It's also odd that the title bar goes off the screen (so the window extends off my screen from the top), instead of the bottom of the window extending off the lower part of my screen. When a window is too big, it's usually the latter thing that happens instead of what your game does. Another commenter mentioned this weird behaviour, too, so it isn't just me. It's not a deal breaker, but it certainly is odd.
And yeah, I'll still keep an eye on your project!