If you open the raw import tool and switch to the luminosity curve you can see a tiny reset icon at the lower-left corner of the curve. If one clicks on that button only the curve gets reset. Further down in that tool you can click on a larger reset button which will reset the whole tool, including the curve. Now open the Curves Adjust tool. It does not have that tiny reset icon for each of the curves but only one big reset button. Clicking on that button resets only one curve. There is no way to reset the whole tool. The user has to switch to each curve and reset it. For consistency within the curve tools and improvement of the workflow within Curves Adjust I would propose the following. Add a tiny reset icon to each curve in the Curves Adjust tool. Clicking on that icon resets only the one curve currently shown. Change the behaviour of the big reset button to reset the whole tool, i.e. all curves. Reproducible: Always
I'm not too favorable regarding the usability of that tiniest of buttons. It is acceptable in the highly cramped space of the Raw import tool. In the curves adjust tool, there is a large "Reset" button only referring to the current curve and at the bottom a "Defaults" button resetting all curves. Better would be a "Reset curve" button and something like "Reset All" or "Reset All Curves" alongside.
Marcel, Why not a contextual menu over view to reset curves ? Gilles Caulier
*** This bug has been marked as a duplicate of bug 277040 ***
Fixed with #277040