  Compact binary supersoft X-ray sources (CBSS) are explained as being
associated with hydrostatic nuclear burning on the surface of a white dwarf
with high accretion rate. This high mass transfer rate has been suggested to be
caused by dynamical instability, expected when the donor star is more massive
than the accreting object. When the orbital period is smaller than ~6 hours,
this mechanism does not work and the CBSS with such periods are believed to be
fed by a distinct mechanism: the wind-driven accretion. Such a mechanism has
been proposed to explain the properties of objects like SMC 13, T Pyx and V617
Sgr. One observational property that offers a critical test for discriminating
between the above two possibilities is the orbital period change. As systems
with wind-driven accretion evolve with increasing periods, some of them may
reach quite long orbital periods. The above critical test may, therefore, also
be applied to orbital periods longer than 6 hours. CAL 87 is an eclipsing
system in the LMC with an orbital period of 10.6 hours that could provide the
opportunity for testing the hypothesis of the system being powered by
wind-driven accretion. We obtained eclipse timings for this system and show
that its orbital period increases with a rate of P/Pdot = +7.2(+/-1.3) X 10^{6}
years. Contrary to the common belief, we conclude that CAL 87 is the first
confirmed case of a wind-driven CBSS with an orbital period longer than 6
hours. The system is probably an evolved object that had an initial secondary
mass of M2i=0.63 solar masses but is currently reduced to about M2=0.34 solar
masses. We discuss evidence that other CBSS, like CAL 83 and V Sge stars, like
WX Cen, are probably also wind-driven systems. This may in fact be the rule,
and systems with inverted mass ratio, the exception.
