Ten desktop test classes drew the same squares and the same 4 x 2
rectangle in private helpers, in two equivalent styles. They now use
TestPrograms.Square, ClockwiseSquare and Rectangle.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The repo mixed variants such as center/centre and color/colour, so a
name could be spelled either way and searches missed half the hits.
Standardize on the US spelling, matching .NET's own APIs (Color, Center).
Wire values owned by other systems keep their spelling: the material
ledger's "Cancelled" hold status and GitHub's "cancelled" job status.
No behavior change beyond the spelling of a few status messages.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Expand Spacing ran its search on the UI thread, so a complex layout froze
the app for minutes with no way out. Run the search on a worker; when it
lasts past 0.3 s, show a small modal window with elapsed time and Cancel.
Cancel, Escape and the close box request cancellation through the
Expander token and the window stays open until the worker stops, so the
layout is never touched afterward. A cancelled run moves no part and
reports it in the status bar instead of the "select two parts" notice.