Selecting a mask group now clears the previous key selection, so Copy/Cut act
on the mask. Pasting masks clears the source mask's vertex selection, so Clear
removes the pasted mask rather than points of the source.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Edit > Copy with masks selected copied the layer, so Paste duplicated it
instead of adding the mask. Masks now go to their own clipboard and Paste
appends them, with unique names, to the selected unlocked layers.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>