Axes drawing correctly for the initial selected configuration. Next, get them to change.
Nit.
Holy snaperoos--the axes and gridlines now update when the drop-down is tweaked.
The legend now redraws on drop-down change.

Also switched the legend so the boxes are on the left; allows the different-sized names to scale.
Wrapped the circle-drawing in a function.
Working on bubble transitions--just checkpointing.
Closer. Getting rid of the higher levels of the heirarchy using exit() on change.
The bubbles change, but some of them are off.
Things are changing on toggle, which is good. Some of the bubbles get "stuck"; need to figure out why.

When things are working, make the bubbles actually transition.