custom property
Whether the surface holds arbitrary content rather than menu rows.
Figma's Custom menu axis. Both variants of Menu/Menu resolve to the
same numbers — 4 padding, 2 gap, Corner-radius/Modal/Medium and
Corner-radius/40 are both 4, and Spacing/List/Section/Gap and
Web/Spacing/XXS are both 2 — so this changes nothing about the surface
and exists so a caller can say which one they are building.
Implementation
final bool custom;