Okay, just playing around again, but I found a really neat technique to extract the foreground. This allows you choose an area of your painting and bring it to the front; whatever you do next will only happen to the front part. (It's like a layer, but you can do this if you realize you need something to act like a layer but don't have one.)

Used path's tool to make the squiggles. I used foreground select and chose a section on the far right to bring to the foreground. The instructions on the tool are pretty self-explanatory. I was then able to smudge that area without worrying about precision. I then used the paintbucket in the same area, but the foreground select made it so that the smudged area couldn't get covered. I think I still like using layers better, but this technique is definitely helpful if you forgot to make one.