I would consider continuing to spritesheet the button itself. The main difference is that each roll-over effect can be separated from all the other spritesheets

I would consider continuing to spritesheet the button itself. The main difference is that each roll-over effect can be separated from all the other spritesheets in the world. Still, an exciting time when we can combine files based on what is the most logical grouping, rather than what is the most efficient. I look forward to the day when HTTP2 rules the world.