You can move them, left or right, and as you move them, a real-time (but low resolution, for compute reasons) preview of the stretch is shown
@Hy for those of us that use large workstations on the client end, how much extra compute would it be to do the full rendering with the sliders? I am wondering about a configuration option that would allow real-time changes from the sliders. This option is not a big enough difference to spend time on if the option would not be easy to implement though.