clear_arrows
lut_walk(nfmep->eventtree, (lut_cb)clear_arrows, (void *)nfmep);
lut_walk(fmep->eventtree, (lut_cb)clear_arrows, (void *)fmep);
static void clear_arrows(struct event *ep, struct event *ep2, struct fme *fmep);
lut_walk(Nfmep->eventtree, (lut_cb)clear_arrows, (void *)Nfmep);
lut_walk(fmep->eventtree, (lut_cb)clear_arrows, (void *)fmep);