  We propose a generic model for thin films and shallow drops of a polar active
liquid that have a free surface and are in contact with a solid substrate. The
model couples evolution equations for the film height and the local
polarization profile in the form of a gradient dynamics supplemented with
active stresses and fluxes. A wetting energy for a partially wetting liquid is
incorporated allowing for motion of the liquid-solid-gas contact line. This
gives a consistent basis for the description of drops of dense bacterial
suspensions or compact aggregates of living cells on solid substrates. As
example, we analyze the dynamics of two-dimensional active drops (i.e., ridges)
and demonstrate how active forces compete with passive surface forces to shape
droplets and drive contact line motion. The model reproduces moving and resting
states of polarized droplets: Drops containing domains of opposite polarization
are stationary and evolve after long transients into drops with a uniform
polarization moving actively over the substrate. In our simple two-dimensional
scenario droplet motion sets in at infinitely small self-propulsion force,
i.e., it does not need to overcome a critical threshold.
