Didn't this use to work?
Code:

println(g.fillR + " " + g.fillG + " " + g.fillB);
 

Error:
Code:

Semantic Error: The field "fillB" in type "processing.core.PGraphics" has default access and is not accessible here.
 

How do i get access to these values?

-seltar

g.fillColor will give you the color (as an 'int'), and g.fill is a boolean that says whether the fill is enabled or not.

so to get fillR etc:
int fillRi = (g.fillColor >> 16) & 0xff;  // number between 0 and 255
float fillR = (float) fillRi / 255.0;  // number between 0 and 1

the others look like:
int fillAi = (g.fillColor >> 24) & 0xff;  // number between 0 and 255
int fillGi = (g.fillColor >> 8) & 0xff;  // number between 0 and 255
int fillBi = g.fillColor & 0xff;  // number between 0 and 255

or you could even use red(g,fillColor) (and the rest) and set the colorMode to use the units that you want.

fillR and fillRi and a bunch of the others were made no longer public because they aren't used consistently across all the renderers. so rather than updating a bunch of variables each time fill() is called for a use that's quite rare (people needing to grab the colors) it's easier to just keep track of one.

as for accessors, the general plan is that g.someName will usually contain the parameter, if it's something that can be stored properly. i.e. g.colorMode contains the current colorMode, or g.strokeWeight contains the current strokeWeight.

some of this can also be seen in the javadoc-in-progress, inside the link to 'core': http://dev.processing.org/reference/

Good call on the documentation ref.