Geometrical finiteness and Veech subgroups of mapping class groups

I will discuss work in progress with Dowdall, Leininger, and Sisto, in which we aim to develop a notion of geometrical finiteness for subgroups of mapping class groups. Motivated by the theory of convex cocompact subgroups, which are precisely those which determine hyperbolicsurface group extensions, I will describe some hyperbolic properties ofthe surface group extensions coming from lattice Veech subgroups.