RGB-only color operations should say they only work in RGB
Submitted by Ari Pollak
Link to original bug (#556206)
Description
From http://bugs.debian.org/502148.
The bottom section of the Colors menu contains items that only work in RGB mode (like Color to Alpha), and are greyed out if the image is not RGB. The manual should mention this fact, since greying the item out doesn't tell the user what they can do to enable the item.
Version: 2.8