  We shall review a novel formulation of four dimensional gauged supergravity
which is manifestly covariant with respect to the non-perturbative
electric-magnetic duality symmetry transformations of the ungauged theory, at
the level of the equations of motion and Bianchi identities. We shall also
discuss the application of this formalism to the description of M-theory
compactified on a twisted torus in the presence of fluxes and to the
interpretation from a M/Type IIA theory perspective of the D=5 --> D=4
generalized Scherk-Schwarz reduction. This latter analysis will bring up the
issue of non-geometric fluxes.
