Module selection 

Selections are always a set (PLAN 3.3). A plain cursor is a set of one empty selection.

Structs

Rectangle

The rectangle a column selection was made from, kept alongside the set so rectangular copy/paste and column-keyed sort can use it. start_* is the anchor corner and end_* the head corner (it may be above or left of the anchor).

Selection

SelectionSet

Non-empty, sorted, non-overlapping selections plus the primary’s index.