A new colour swatch starts from the one you selected.
Fixed in this release
+ in the swatch panel copies the selected swatch. The New Color Swatch dialog always opened
as a copy of the fifth swatch in the library (usually C=100 M=0 Y=0 K=0), whatever was selected.
It now starts from the colour swatch selected in the panel, as InDesign does, with its type: a
spot colour's copy opens as Spot, a process colour's as Process. When the selected swatch is one
the dialog cannot edit — a gradient, a tint, a Lab or mixed-ink colour, or one of the four fixed
swatches ([None], [Registration], [Paper], [Black]) — or nothing is selected, it starts from the
library's first process or spot colour in CMYK or RGB, and in a library without one from grey. A
gradient in that fifth place was opened as if it were a colour.
Typograph developers notes
TYP-1325: new_swatch_source() (src/swatchdialog.ts) picks what a new colour swatch copies
(a SWATCH of model PROCESS or SPOT in CMYK or RGB), and the dialog takes the copy's type;
Swatch_Edit_Dialog takes the selected swatch's uuid as a sixth constructor argument
(copy_from_uuid), which the swatch panel's add_swatch() passes.