Sometimes when you barely move the mouse it would slide the things completely off the screen.. I tried refreshing to make sure it wasn't the fact I was using a track pad on my laptop, but it kept doing it..
It's a very minor problem but can make the game a bit difficult when it keeps happening. >x< So I thought I'd let you know.
Overall it's a really good game, and I had a lot of fun playing it.. I'm surprised I haven't played it before! I love puzzle games.