Drop shadow, option to preserve underlying transparency.
Often, I want product stills to cast their shadows on products down the layer index. But only on the parts that have pixels, to give the appearance of them being in close proximity (like an ambient occlusion pass). Right now the Drop shadow drops its shadow everywhere, regardless of what's underneath it.
A checkbox option to only cast shadow on layers that have pixels would be swell.
That is actually an awesome idea. A track transperency swith but only for Layer Styles.