Attempt at themeable tristate checkboxes

My method is to create a checkbox, manually lay it out and then
get a bitmap from its drawable cache.
As far as I can tell, it is being themed, colorwise, but not
sizewise. It is rather small. So I set a size on it first, but
there lies the problem. If I let it be the size it chooses, it will
center itself in its drawable, and if I fix its size, it will sit
far to far to the right, trimming off the tail of the tick.
I can't garantee it works on all devices either, but it doesn't
look bad on mine.