The preset comes with an electric field applied to the sample and very long scattering times. With a click on run you see the effect of the electric field is to carry the distribution of occupied states off the screen to the left.
Now change the inelastic scattering time tau-i to 1.0e+00 ps, initialize, and run again. The distribution doesn't get very far before the scattering returns electrons from the left side of the Fermi surface to the right. A steady state is quickly reached in which the Fermi sea has been displaced to the left by an amount e*E*tau/h-bar.