  Phase separation of colloid-polymer mixtures, described by the Asakura-Oosawa
(AO) model, confined in a thin slit pore is studied by grand-canonical Monte
Carlo simulation. While one wall is a hard wall for both particles, at the
other wall there acts an additional repulsive potential on the colloids only.
Varying the strength of this potential, a crossover from capillary condensation
to an interface localization transition is found. The latter occurs under
conditions where in the bulk almost complete phase separation has occurred.
