Deformation classes in generalized Kahler geometry

We introduce natural deformation classes of generalized Kahler structures using the Courant symmetry group. We show that these yield natural extensions of the notions of Kahler class and Kahler cone to generalized Kahler geometry. Lastly we show that the generalized Kahler-Ricci flow preserves this generalized Kahler cone, and the underlying real Poisson tensor.