Tickit::Pen          T_PTROBJ_OR_NULL
Tickit::Rect         T_PTROBJ
Tickit::RectSet      T_PTROBJ
Tickit::RenderBuffer T_PTROBJ
Tickit::StringPos    T_PTROBJ_OR_NULL
Tickit::Term         T_PTROBJ

INPUT
T_PTROBJ_OR_NULL
        if (!SvOK($arg)) {
            $var = NULL;
        }
        else if (SvROK($arg) && sv_derived_from($arg, \"${ntype}\")) {
            IV tmp = SvIV((SV*)SvRV($arg));
            $var = INT2PTR($type,tmp);
        }
        else
            Perl_croak(aTHX_ \"%s: %s is not of type %s\",
                        ${$ALIAS?\q[GvNAME(CvGV(cv))]:\qq[\"$pname\"]},
                        \"$var\", \"$ntype\")