  We present a Monte Carlo approach to soft-gluon resummation at subleading
color which can be used to improve existing parton shower algorithms. At the
single-emission level, soft-collinear enhancements of the splitting functions
are explicitly linked to quadratic Casimir operators, while wide angle
single-soft enhancements are connected to nontrivial color correlators. We
focus on a numerically stable implementation of color matrix element
corrections to all orders and approximate the virtual corrections by requiring
unitarity at the single-emission level. We provide a proof-of-concept
implementation to compute nonglobal event shapes at lepton colliders.
