Selection Paint

Paint curves or control paints to use as masks for the other tools. The selection visibility can be controlled by the Selection Opacity option in the Viewport Overlays.

By default the selection sets a new selection. The selection paint can be extended by holding Shift and it can be subtracted by holding Ctrl while painting.

Brush Settings

Direction

Determines whether to set a new selection or remove from it. It can be toggled holding Ctrl while painting.