  The problem of a thin superconducting film in a parallel magnetic field,
first discussed in the classical paper by Ginzburg and Landau for temperatures
close to the critical, is revisited with the help of the microscopic BCS theory
for arbitrary temperatures taking pair-breaking and transport scattering into
account. While confirming experimental findings of the $T_c$ enhancement by the
magnetic field, we find that the transport scattering pushes the phase
transition curve to higher fields and higher temperatures for nearly all
practical scattering rates. Still, the $T_c$ enhancement disappears in the
dirty limit. We also consider intriguing changes, such as re-entrant
superconductivity, caused to the phase boundary by pair-breaking magnetic ions
spread on one of the film faces. These features await experimental
verification.
