Wet paint you can smear and mix — real pigments through the spectral Kubelka–Munk engine. Pick a palette (Golden acrylics or classical oils), click a well to arm a squirt, click a surface to drop a glob of paint, then stroke through the glob to load the brush — just like a real palette.
Strokes on the palette pick up and drop paint just like the canvas.
Dry the wet layer to bank it as a substrate, then glaze over it with a medium-diluted pigment. Dried layers can be undried (edited), deleted or reordered; Undry needs an empty wet layer.