@anon41087856 : Nice work and the only doubt I currently have is already asked and answered (shadows/highlight/midtones order).
Had a quick go at this one a it seems to be much smoother and thus easier to use and correct than the current colour balance module.
@Underexposed:
You can check yourself when a Pull Request (new/changed functionality) has been merged (made available) into the development branch: Go to the darktable section on GitHub, click on Pull requests, click on Closed and set the sort order to Recently updated
In this specific case you see, near the top, Colorbalancergb: rework the mask method. If you hover over the:
#8620 by aurelienpierre was closed 19 hours ago
part you see the exact date/time it was merged. In this case Apr. 8, 2021, 3:59 PM UTC
I’m assuming you build your own (based on this): If you build your version before the afore mentioned date/time you need to pull the changes, rebuild and reinstall.
At the moment I’m on 3.5.0+1616~ge9302dbf7 and it has all the latest changes mentioned above.