Select the Bezier Mask tool

Option-B

Switch between the Bezier Mask and B-Spline Mask tools

Option-B

Close mask

C

Add a point to the path

Double-click a path

Add a point to the path

Command-click a path

Convert a point to linear

Command-click a point

Create tangents on a point

Command-drag a point

Scale tangents proportionally

Command-drag a tangent handle

Break or relink a tangent handle

Option-drag a tangent handle

Constrain a tangent to 45 degrees and original value

Option-Shift-drag a tangent handle

Cancel shape drawing and delete the open shape

Escape

Exit shape-drawing mode

Return