The tool allows you to create a volumetric mesh solid instantly. Draw as you do with Ink/Stroke tool. The outermost control points will decide the shape.
A. Planar: Lay out plane with non-drawing hand trigger before drawing. Half pull the trigger to snap the plane at 45 degree increments. When you draw, a filled shape will be created from the border. You can extrude the planar surface in edit mode.
The rest of the options work the same as Stroke tool.