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tokens: binary components are not hidden in the glare of an accretion disk. Hence, the short-period hot subdwarf binaries represent an important progenitor channel of CVs. In fact, Schenker (2005) postulates that the CVs below the period gap are the product of post-subdwarf binary evolution. On the other hand, the hot subdwarfs with massive WD companions are potential progenitors of Type Ia supernovae (see Iben Tutukov 1984 ; Webbink 1984 , and for the most recent candidates see Geier et al. 2013 ; Vennes et al. 2012 ). Therefore, they are an important ingredient in understanding Type Ia supernovae. Establishing the accurate masses of both components of post-common-envelope binaries (PCEBs) is the only empirical way to constrain the efficiency parameters of the CEE phase. Furthermore, detailed investigation of hot subdwarf binaries is crucial when determining their masses for comparison with their theoretically proposed evolutionary channels, as well as to test the binary-population synthesis models. However, most of the hot subdwarf binary systems with known orbital periods are single-lined spectroscopic binaries, making it impossible to reliably determine the absolute masses of their components. Among the PCEBs, 15 eclipsing binary systems have been found to date, which are comprised of a hot subdwarf primary (sdO or sdB star) and a low mass secondary, either a late dM or a brown dwarf (BD) (for the most recent discoveries see Schaffenroth et al. 2013 ; Barlow et al. 2013 ; Schaffenroth et al. 2014 , 2015 ). Such eclipsing systems are known as HW-Vir-type binaries after the prototype. In addition to eclipses, HW-Vir systems are notorious for having a very strong “reflection effect”. This reflection effect, characteristic for all close binaries that comprise a very hot primary and much cooler secondary, is due to the high contrast in the temperatures between the heated and unheated hemisphere of the secondary star. As the secondaries in these systems are supposed to be orbiting synchronously, one side of the cool secondary star is constantly being irradiated by the strong ultraviolet (UV) flux of the hot-subdwarf primary. The light-curve solutions of HW-Vir-type systems imply that the temperature of the cool companion around the substellar point is increased up to 10 00020 000 K ( Hilditch et al. 2003 ; Kiss et al. 2000 ). However, the detection of spectral features from the irradiated secondary in HW-Vir-type systems is hampered by the contamination from the much hotter subdwarf primary. Recently, the eclipsing PCEBs gained even more attention, because nearly all systems with accurate eclipse-timing measurements, which have long enough data sets, are found to show apparent orbital-period changes ( Kilkenny 2014 ) that might indicate the presence of circumbinary planets (see Beuermann et al. 2010 , 2012a , b , for the most convincing cases). The claims of circumbinary planets in short-period sdB+dM/BD systems, as well as various planets in close