The Positioning Sequence
From HLKitWiki
[Context: HL Kit … Basic Concepts and Terminology … Manipulation of Visual Elements]
The Position Script
Every visual container possesses a "position" script, which means the script is possessed by every template, layout, panel, and sheet. The Position script serves one specific purpose - to properly size, position, and configure all of the child elements within the visual container. Not every visual container needs to define a position script, since the HL engine performs some actions automatically, but most visual containers will perform at least some operations within their Position, and some will perform extensive operations to properly setup the visual elements within them.
Recursive Descent Through Hierarchy
The HL engine imposes a strict sequence for positioning all