Operating system: Windows-10-10.0.17763 64 Bits
Graphics card: GeForce GTX 1080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 430.64
Broken: version: 2.80 (sub 72), branch: blender2.7, commit date: 2019-05-28 21:07, hash: rB9bae9b634ec6
Worked: Probably never
Short description of error
Brush adjustment cancel operator is hardcoded, not adjustable in Keymap editor. This results in big issues when someone wants to assign for example brush radius adjustment to any key combination which involves right mouse button, as RMB release is hardcoded to be cancel. Therefore for example assigning brush radius control to Alt+RMB results into the adjustment being discarded on release, instead of applied. This is very inconsistent as for example Alt+LMB or Alt+MMB work fine.
Exact steps for others to reproduce the error
1, Assign Image Editor brush Radial Control operator to Shift+RMB
2, In Image Editor paint mode, use Shift+RMB to adjust brush size
3, Notice that upon RMB release, the adjustment is discarded instead of applied.
Result: Brush control modal map is hardcoded to have RMB as cancel operator.
Expected: Brush control modal map parameters are exposed in keymap editors, like it is the case with all other modal maps (Gestures, Transforms, Eyedropper etc...)