Color Curves

Am I missing something or is there really no way to use curves in the age old way having RGB channels ganged?

I have a question in the same vein as the above.
Is there any way to force the curves to stay as RGB when sampling a color point on the image?

I want to get the corresponding points on the RGB curves so that I can perform a correct white balance. But if they keep changing to whatever the color is, I can't use curves for that and it's really annoying since it's the best tool for the job.

Any ideas ?

Ok just checking back to check it really is the truth?
Can't apply an S curve like any other NLE?

I know in some circumstances it can be helpful to make fine adjustments to luma without affecting chroma, but 9 times out of 10 I just want plain old curves.
Am I alone here?

It's a lot easier to pull back an unwanted saturation boost, post curves, than it is to try and manually match all the individual curves.