commit https://github.com/vim/vim/commit/0ba75a9714884895b2ac09733158c47544a8dfb9 Author: Bram Moolenaar <Bram@vim.org> Date: Fri Feb 19 23:21:26 2016 +0100 patch 7.4.1360 Problem: Can't remove a callback with ch_setoptions(). Solution: When passing zero or an empty string remove the callback.

TYPEMAP
VIWIN	T_VIOBJNOMUNGE
VIBUF	T_VIOBJNOMUNGE

INPUT
T_VIOBJNOMUNGE
	if (sv_isa($arg, \"${ntype}\")) {
	    IV tmp = SvIV((SV*)SvRV($arg));
	    $var = INT2PTR($type, tmp);
	    if (!tmp)
		croak(\"$ntype no longer exists\");
	}
	else
	    croak(\"$var is not of type ${ntype}\")