I knew it was CRC32

Congrats on the release. A suggestion for future builds: Keep the preview window up top, centered, and move the item list directly underneath it. Make it the same width as the preview window, have the items in 3 columns rather than 2, and have a scrollbar on the side. That would keep the GUI a little more compact for smaller screens and wouldn't have so much empty space on the left side.
EDIT: Perhaps the option for a grid, and also the ability to drag and draw.