> i wonder, is what you're proposing the same as the 'group layers
> masks' described in
> Is this already covered by
In photoshop it is a single layer that docks to the layer (or multiple
layers) beneath it, acting as a mask.
In PS it is activated by Ctrl+LMB (from memory) on the edge between two
Layer group masks would achieve the same thing, and sounds easier to
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