I’m testing the new version 2.52 ( alpha 2 ).
I can insert a key in composite node where an input field is placed. ( press the ikey ).
But is it possible to input a key in a graphic field like the graphic in “RGB Curves node” so I can change the Red color spline in time?
That’s a great idea. I’m looking into it
I guess there is no corresponding value field for those types of edits (to record a change in).
Unfortunately nothing is animatable in nodes (I thought everything was subject to keyframes now?), thats a shame.
Hang about, nope wrong I just tried running 2 RGB curve nodes through a mix node and I COULD animate that Factor or Mix value with a key frame.
Effectively dissolving between the 2 states.
Sooooo, it would seem you need a Factor or value field to change not a graphic representation of a value 
