  We numerically study a one-dimensional conserved growth equation with
competing linear (Ehrlich-Schwoebel) and nonlinear instabilities. As a control
parameter is varied, this model exhibits a non-equilibrium phase transition
between two mounded states, one of which exhibits slope selection and the other
does not. The coarsening behavior of mounds in these two phases is studied in
detail. In the absence of noise the steady-state configuration depends
crucially on which of the two instabilities dominates the early time behavior.
