  The threshold scan of top pair production at a future lepton collider allows
to determine several Standard Model parameters with very high precision. The
recent completion of the third-order QCD corrections to the inclusive top-pair
production cross section demonstrated that strong dynamics are under control.
We investigate effects from P-wave production and Higgs contributions at third
order and from QED and the nonresonant production of the physical
$W^+W^-b\bar{b}$ final state at first order. We discuss the sensitivity of the
cross section to the top mass, width and Yukawa coupling as well as to the
strong coupling.
