The new flood-fill
I want to make the cold light behind the vendor even colder. So I slide two fingers to the right on the paint layer (it turns purple, which indicates it’s a reference layer). Then I use the new Recolor tool in a new layer that I set to Color mode. Each time I use it, I can choose the colour it should flood-fill to and how much it should bleed out, and repeat it for all the areas I want to adjust.