  The nature of a metal-insulator transition tuned by external gates in quantum
Hall (QH) systems with point constrictions, as reported in recent experiments
of Roddaro et al [1], is examined. We attribute this phenomenon to a splitting
of the integer edge into conducting and insulating stripes, the latter wide
enough to allow for the stability of the edge structure. Inter-channel impurity
scattering and inter-channel Coulomb interactions do not destabilize this
picture.
