  The spectrum and the eigenstates of a finite 2D tight-binding electronic
system, with Dirichlet boundary conditions, in magnetic field and external
linear potential are studied. The eigenstates show an equipotential character
and may cross the plaquette in the direction perpendicular to the electric
field. When leads are added to the plaquette, the channels carrying the current
may be shortcut by equipotentials, resulting in additional plateaus situated
inbetween the usual IQHE plateaus. This idea is confirmed by a numerical
calculation within the four-terminal Landauer-B\"{u}ttiker approach.
