How about getting colors in the Curve editors for all GUI curves?
I think this could be a great addition to user feedback, and could distinguish better those curves dedicated to color or height from those used for vectors, which I suppose can stay the way they are.
This is how it could look in the RGB Curve Editors.
And for brushes.
What do you guys think?
I think that looks like a good way to visually indicate the effects of the curves. +1 from me
It seems that this will not receive much more approval. 
What feedback did you get from the developers when you put it to them ?
Very good idea
I like it, I don’t think any other app has something like this, it’s useful and it would be unique to blender.
I support the idea.
Very smooth, and quite fancy as well.
I also approve providing that the line remains as visible as possible.
It looks fancy, but I don’t find it too useful, as the colours just make sense in white areas. In other colours in your render it could lead to confusion.
@Richard Marklew. I didn’t get any more feedback than the need to publish this here in BlenderArtists, before getting into the ToDo tracker.
Here’s the post in the tracker.
https://developer.blender.org/T43653
It remains closed by now, unless some kind of super power reopens it, I think.
@Auuman Anubis. Actually this is already used in other softwares as well. Here’s a video about compositing, where you can see these tools in action.
@DavidGasku. The RGB curves are always intended to vary the color from current colors. This visual indication is for the user to know “where” is it going when editing curves, and “how much” of the color is being added.
