When an XGL Gcache decomposes a polygon with edges, some edges are rendered incorrectly for xgl_gcache_multi_simple_polygon().
Workaround: Set the XGL_GCACHE_USE_APPL_GEOM to TRUE. Alternately, use xgl_gcache_polygon() instead of xgl_gcache_multi_simple_polygon() and turn off the XGL_GCACHE_SHOW_DECOMP_EDGES when creating the GCACHE context.