  We show that the semiclassical dynamics of an electronic droplet confined in
the plane in a quantizing inhomogeneous magnetic field in the regime when the
electrostatic interaction is negligible is similar to viscous (Saffman-Taylor)
fingering on the interface between two fluids with different viscosities
confined in a Hele-Shaw cell. Both phenomena are described by the same
equations with scales differing by a factor of up to $10^{-9}$. We also report
the quasiclassical wave function of the droplet in an inhomogeneous magnetic
field.
