See the screenshot: https://i.imgur.com/n4rtpo9.png
This happen by sliding the horizontal slider for setting the brightness. It may also happen with the Hue, but I can't test it because it skips over too much values, but I assume it would have the same bug.
I guess it uses floats, but only shows an int value. Still, -0 should be 0.
I can also type everything that I want in the inputboxes beside the sliders. It does not cause any problem, but it should be avoided.
I have version 2.0.1
I think this should be fixed in the latest release (2.0.3), at least for the Qt5 interface ints are used so there shouldn't be a problem there, for the Gtk3 interface is a bit different since it needs some conversion for the sliders.
Regards,
Paulo