Just as stated in the title, I've been using PS since 3.0. I taught it in college for twenty-five years and I'm still waiting for this feature. I know you can do this. Frequently, I want to burn in just shadows, midtones or highlights, but being confined to black, or gray looks very unnatural. It would be so nice to sample the color in the area and use that color combined with gray to burn in just the shadows, midtones, or highlights. If there's a simple workaround already in PS, please let me know.