  We study the glass transition of binary mixtures of dipolar particles in two
dimensions within the framework of mode-coupling theory, focusing in particular
on the influence of composition changes. In a first step, we demonstrate that
the experimental system of K\"onig et al. [Eur. Phys. J. E 18, 287 (2005)] is
well described by point dipoles through a comparison between the experimental
partial structure factors and those from our Monte Carlo simulation. For such a
mixture of point particles we show that there is always a plasticization
effect, i.e. a stabilization of the liquid state due to mixing, in contrast to
binary hard disks. We demonstrate that the predicted plasticization effect is
in qualitative agreement with experimental results. Furthermore, also some
general properties of the glass transition lines are discussed.
