It's an option. When you click on the thumbnail, you're taken to a gallery page, near the top you will see:
Size: constrained · [original]
Click "constrained" and you'll get the behaviour I described. To see the original size you can click on the resized image and it links directly to the original image file. -- Developer: Tomato/MLPPP, Linux/MLPPP, etc »fixppp.org
