And one more fix to the method, for which I added a variation of

DBNMSrPaintPlane() where if "tile" is non-NULL then "plane" can be
NULL;  the hint tile does not get set but the routine can be called
without knowing the plane other than that the tile is in it somewhere.

drc/DRCbasic.c

@@ -375,9 +375,7 @@ areaNMCheck(tile, arg)
 
 	TTMaskSetOnlyType(&mask, TiGetLeftType(tile));
 	TTMaskSetType(&mask, TiGetRightType(tile));
-	if (DBSrPaintNMArea((Tile *)tile,
-		arg->dCD_celldef->cd_planes[arg->dCD_plane],
-		dinfo, arg->dCD_rlist,
+	if (DBSrPaintNMArea((Tile *)tile, (Plane *)NULL, dinfo, arg->dCD_rlist,
 		&mask, areaNMReject, (ClientData)tile) == 0)
 	    return 0;
     }