I implemented a WPF control to look like a winform control and ran into a issue of the vintage control looking perfect at an odd (9px by 9px) native pixel size that gets distorted by WPF when rendered at different scaling.

Visual Studio's + sign expanders have had this bug for years that was finally fixed by changing to a chevron shape in 2022. Clearly this problem bugged someone on the dev team hence the fix. =)