a = <featuring_a_depth_buffer> ? false : true;
b = <meant_to_compile_under_msvc6> ? false : true;
if (a && b) then
well, i guess THURP (see sig) could easily suit your need -- just write yourself a flat shading spanner -- should be a 5min work using the present spanners as a template. AAMOF, adding depth buffering should be other 5 min work, just never needed one so far.