  We determine the possible masses and radii of the progenitors of white dwarfs
in binaries from fits to detailed stellar evolution models and use these to
reconstruct the mass-transfer phase in which the white dwarf was formed. We
confirm the earlier finding that in the first phase of mass transfer in the
binary evolution leading to a close pair of white dwarfs, the standard
common-envelope formalism equating the energy balance in the system, does not
work. An algorithm equating the angular momentum balance can explain the
observations. This conclusion is now based on ten observed systems rather than
three. With the latter algorithm the separation does not change much for
approximately equal mass binaries. Assuming constant efficiency in the standard
\alpha-formalism and a constant value of \gamma, we investigate the effect of
both methods on the change in separation in general and conclude that when
there is observational evidence for strong shrinkage of the orbit, the
\gamma-algorithm also leads to this. We then extend our analysis to all close
binaries with at least one white dwarf component and reconstruct the mass
transfer phases that lead to these binaries. We find that all observations can
be explained with a single value of \gamma, making the \gamma-algorithm a
useful tool to predict the outcome of common-envelope evolution. We discuss the
consequences of our findings for different binary populations in the Galaxy,
including massive binaries, for which the reconstruction method cannot be used
(abbriged).
