Operating system: Linux-5.3.0-40-generic-x86_64-with-debian-buster-sid 64 Bits
Graphics card: GeForce GTX 980 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 435.21
Broken: version: 2.82 (sub 7), branch: master, commit date: 2020-02-12 16:20, hash: rB77d23b0bd76f
(as well as the latest alpha: version: 2.83 (sub 5), branch: master, commit date: 2020-03-02 23:59, hash: rBfe7c4fb4a2d5)
Worked: 2.80 (Checkbox existed in Image Editor brush settings, but had NO effect on brush behavior)
Short description of error
In the 3D Viewport as well as the Properties Editor while in Texture Paint mode, all brushes offer the "affect alpha" option in the "Advanced" section of the Brush Settings. In the Image Editor that option is missing from the "Advanced" section for no apparent reason.
Exact steps for others to reproduce the error
Open Blender with factory settings. Switch to "Texture Paint" tab. Compare the "Advanced" section of the active brush's tool settings in the Image Editor to that in the 3D Viewport or Properties Editor.
Surely this has to be a well-known issue and exists only due to technical limitations of some kind.
What should I tell my students why this inconvenience exists and when it will be addressed?