Okay, I just need to come in here and tell you THANK YOU ♥ for introducing me to the concept of clipping mask (though it's called something else in my program) because OH MY GOD THAT MAKES IT SO MUCH EASIER TO COLOR IN THE LINES ;o; ♥ ♥ ♥

(Before, I had been doing, like... copy layer, lock layer, which works well enough but doesn't have a really good keyboard shortcut and looks a lot clumsier in the layers section. orz)