  Using Brownian Dynamics (BD) simulations we investigate non-equilibrium
transitions of sheared colloidal films under controlled shear stress
$\sigma_{\mathrm{xz}}$. In our approach the shear rate $\dot\gamma$ is a
dynamical variable, which relaxes on a timescale $\tau_c$ such that the
instantaneous, configuration-dependent stress $\sigma_{\mathrm{xz}}(t)$
approaches a pre-imposed value. Investigating the dynamics under this
"feedback-control" scheme we find unique behavior in regions where the flow
curve $\sigma_{\mathrm{xz}}(\dot\gamma)$ of the uncontrolled system is
monotonic. However, in non-monotonic regions our method allows to {\em select}
between dynamical states characterized by different in-plane structure and
viscosities. Indeed, the final state strongly depends on $\tau_c$ relative to
an {\em intrinsic} relaxation time of the uncontrolled system. The critical
values of $\tau_c$ are estimated on the basis of a simple model.
