Loading/Adding/Subtracting/Intersecting Layers As Selections
To load a layer as a selection, press-and-hold the Ctrl (Mac: Command) key and click on the layer’s thumbnail in the Layers panel.
To add a layer to an already existing selection, press Ctrl Shift (Mac: Command Shift) and click on the layer’s thumbnail.
To subtract a layer from a selection, press Ctrl Alt (Mac: Command Option) and click on the layer’s thumbnail.
To intersect the selection press Ctrl Alt Shift (Mac: Command Option Shift) and click on the layer’s thumbnail.
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