Hi, Alyosha. If you mean that you don't like borders at all for some windows, then you can disable from the configurator -> window rules. See appearance -> frame type -> title only.
But maybe this is not what you want. How about browsing theme's code, located sawfish-source/themes/(whatever-theme)/theme.jl ? I don't know how to hack themes. Poka, Teika (Teika kazura)
