Only by using the up and down arrows for the numerical value can I get =/-500 values. Moving the sliders alone gets me 0-100 (%)
because there’s no check for users entering stupid values;)
you might file an issue if you want it to be fixed…
0-255 is only the range for 8bit images. If you go to 16 bit (0-65.536) or even 32 bit you can have much bigger values.