XnView Software

XnViewMP 1.4.5 64bit
Windows11 (22H2), display resolution 3840x2160, win scaling 150%

Instruments - сurves
corner points are invisible

to reproduce 1. grab corner point
2. drag it somewhere
it will be repositioned, but not possible to see where as there is no corner point marker
3. add new point (for testing)
new point will be added
curve will pivot against invisible corner point



Suggestion

• add corner points marks
  • last 2 points should always turn into corner points
  • it should not be possible to delete last 2 points
  • it seems that if the corner point is disconnected from the vertical axis, the curve will turn into a straight horizontal one
    although, not sure why Lightroom only has this for the left corner point
    

    

Related

• suggestions
  Instruments - mono mixer - add Preserve luminosity
  Instruments - white balance - rework
  Instruments - curves - add marks for corner points (current post)
  Instruments - effect scaling - unify settings and behaviour
  - done -
  Instruments - effect scaling - improve intensity (1.8.2)

I would suggest to mark corner-points by default like in Gimp: So the corner-points are easy to grab from the first moment.