code: func goTreeModelFilterFuncs(filter *C.GtkTreeModelFilter, iter *C.GtkTreeIter, data C.gpointer) C.gboolean {
  	id := int(uintptr(data))
  
  	treeModelVisibleFilterFuncRegistry.Lock()
  	r := treeModelVisibleFilterFuncRegistry.m[id]
  	treeModelVisibleFilterFuncRegistry.Unlock()
  
  	goIter := &TreeIter{(C.GtkTreeIter)(*iter)}
  	return gbool(r.fn(
  		wrapTreeModelFilter(glib.Take(unsafe.Pointer(filter))),
  		goIter,
  		r.userData))
  }
docs: //export goTreeModelFilterFuncs