From Xojo Documentation
| This item has been deprecated since version 2016r1 and should no longer be used.
Please use RGBSurface as a replacement.
Pixel has been updated to properly support alpha channels by taking them into account when rendering them. Additionally, Pixel with always return Nil for pointers with alpha channels. For pictures without alpha channels, the mask functionality will continue to work.
In macOS builds, you can read from Graphics.Pixel only for Graphics objects obtained from a Picture. Doing so from other Graphics objects will result in an UnsupportedOperationException. You can however assign a value to Graphics.Pixel for a Graphics object obtained from any object.
This example assigns the color of a particular pixel in a Canvas control to a variable.