on their chemical abundances, abundance gradients, and tidal tails of dSphs (for most recent reviews see e.g. [@koc09] and [@tol09]) have triggered numerous numerical models. Although they are advanced since [@hen04] to 3D hydrodynamics (see e.g. [@mar08] and [@rev09]), they still lack of a self-consistent treatment of both, internal processes, as e.g. SF self-regulation (see sect.\[intro\]), and the environmental influences as e.g. tidal effects, external gas pressure, gas inflow, etc.

In a recent paper [@rev09], e.g. a large set of DG models is constructed with the method of smooth-particle hydronamics (SPH), but considers all of them in isolation. In most of their models sufficient gas mass is retained and can fuel further SF epochs, if it would not be stripped of by ram pressure or tidal forces, as the authors mention. Those models that fit the presently best studied dSphs Fnx, Car, Scl, and Sex, are than chosen as test cases for further exploration. Although their results do not deviate too much from the further observational data, in addition to the already mentioned neglections, three further caveats exist: 1) If models are selected according to any agreement with one or two observed structural parameters, it is not surprising if also 