I just thought i'd add that I just swapped my Antuino over to openGLCD, from the deprecated original GLCD. I'm no programmer, just trying to be a tinkerer and teach myself. I've figured out how to make a testing branch on github. If anyone else would be willing to make sure my changes work (they do here, at least), I would greatly appreciate it! As Bruce says - Use at your own risk!
My testing branch is https://github.com/woodjrx/antuino/tree/testing
I love the idea of the lookup table - but I need to get a step attenuator to test against, first!