Added: Follow the surface behind (on by default). Picking a see-through material, such as a stocking over skin, sets its shadow colours so the layered result shades like one surface of the colour you see. The shadow of the surface behind is read from that material's own settings. The toggle is in the Shading tab's Shadow group, and the sampling area on the Colour tab tells you which material it shaded over and at what opacity, or why it could not.
Added: Surface behind blend slider under the toggle (0–100%, 100 % by default). 0 % keeps the shadow chosen from the material alone; 100 % is the full surface-behind result; values between mix the two evenly in perceived colour. It is saved with presets and reset by the reset button, and presets saved earlier keep 100 %.
Fixed: with the NDMF preview on (Modular Avatar), clicking a previewed mesh, such as a body whose blend shapes a Shape Changer drives, picks that mesh instead of passing through to a tail or hair behind it.
Fixed: the sampled opacity of lilToon and Poiyomi materials includes the alpha mask and lilToon's main 2nd/3rd layer alpha modes.
Fixed: in Linear colour-space projects, which every VRChat project is, colours are read from and written to materials as the sRGB values Unity stores. Shadow and other colours were written too dark and too high in chroma before, and a textureless material's tint was sampled darker than it renders.