Previously, it was not clear where the boundary of the StickWidget was when interacting outside of the circle. This aims to restore the gray square present in the Wx-era.
SPDX standardizes how source code conveys its copyright and licensing
information. See https://spdx.github.io/spdx-spec/1-rationale/ . SPDX
tags are adopted in many large projects, including things like the Linux
kernel.
sowens99