graphics scaling error, deeper than turtle graphics?

I am using a Circuit Playground Bluefruit with TFT Gizmo, adafruit-circuitpython-bundle-9.x-mpy-20241206.zip, and the "Turtle Gizmo Setup" code provided by John Park at https://learn.adafruit.com/turtle-graphics-gizmo/. See the attached file renamed from .txt to .py. From the code:

Issue: On a 240x240 pixel display with (0.0, 0.0) at the center, the
border pixels should include x,y values of 119.1 to 119.9 (actually
a slightly wider range, but at least those values). The following
code should make a visible square in both cases and does not. The
119.9 case is missing the right side of the square.

This was reduced from a more complicated program that required the
correct scaling of the 240x240 display including the border pixels.

[turtle_scaling_issue.txt](https://github.com/user-attachments/files/18049896/turtle_scaling_issue.txt)

Start by reading turtle_scaling_issue.txt and the Turtle Gizmo Setup example, then reproduce the two square cases on the 240x240 TFT Gizmo display. Done means both cases render a visible square, including the right side for the 119.9 boundary value, while preserving the intended border scaling.

Written by the indexing model from the issue text.