Select the B-Spline Mask tool

Option-B

Switch between the Bezier Mask and B-Spline Mask tools

Option-B

Close the mask

C

Add a point to the path

Double-click a path

Add a point to the path

Command-click a path

Adjust a B-Spline point bias

Command-drag a B-Spline point

Switch a B-Spline point bias

Command-click a B-Spline point

Cancel shape drawing and delete the open shape

Escape

Exit shape-drawing mode

Return

Select the Bezier Mask tool

Option-B

Show/hide mask control points

Apostrophe (’)