Currently levels filter mask middle slider (grey) can be set from 10 to 0.1. Maybe it is possible to change that limit from 0.1 to 0.001. Such extreme setting can be useful when working with 32bit images.
Thanks for the report, I'll look into it.
Eek, this even unearths a real bug: a value of 0.001 is saved as 1.
Git commit de183bb43576d662a916ef4af66130a038d358d0 by Boudewijn Rempt. Committed on 19/01/2017 at 09:55. Pushed by rempt into branch 'master'. And actually save the gamma value correctly; unless you moved the sliders, the value taken would be 1.0 M +1 -1 plugins/filters/levelfilter/kis_level_filter.cpp M +6 -3 plugins/filters/levelfilter/wdg_level.ui https://commits.kde.org/krita/de183bb43576d662a916ef4af66130a038d358d0
Git commit d2d19b5be3efe5ad48ed237b9b324642009146a7 by Boudewijn Rempt. Committed on 19/01/2017 at 10:00. Pushed by rempt into branch 'krita/3.1'. And actually save the gamma value correctly; unless you moved the sliders, the value taken would be 1.0 M +1 -1 plugins/filters/levelfilter/kis_level_filter.cpp M +6 -3 plugins/filters/levelfilter/wdg_level.ui https://commits.kde.org/krita/d2d19b5be3efe5ad48ed237b9b324642009146a7