Grid Improvement 101
Your grid does not bisect the scene horizontally or vertically. This makes it challenging (downright maddening) to center any object or text. In its current form, your grid is 8 & 2/5ths wide by 4 & 3.5/5ths tall.
I propose you change the grid (not the scene size, just the grid overlay) to numbers easily divisible by 2.
For example, a scene 8 squares wide would have 4 on the left side, 4 on the right, and a line clearly bisecting the middle of the scene. A scene 4 units tall would have 2 squares below the midline, and 2 squares above.
If this doesn't work out due to some kind of aspect ratio problem (think latitude/longitude on a flat map), then at least fix the width. Centering images horizontally is more aesthetically pleasing than centering them vertically.
Alternatively - leave the grid the way it is, and provide an optional, additional overlaid line in a highly visible color that clearly bisects the scene vertically and horizontally.
Thank you for your consideration, I believe it'd be a simple and user friendly change.