  Pinning and depinning of drops on an inclined heterogeneous substrate is
studied as a function of the inclination and heterogeneity amplitude. Two types
of heterogeneity are considered: a hydrophobic defect that blocks the droplet
in front, and a hydrophilic one that holds it at the back. Two different types
of depinning leading to sliding motion are identified, and the resulting
stick-slip motion is studied numerically.
