`UILayout.operator_menu_enum()` now returns the operator properties, just like `UILayout.operator()`. This makes it possible to set options for the operator displayed in the menu. In C it can be done through the new `uiItemMenuEnumFullO()` or `uiItemMenuEnumFullO_ptr()`. It's reasonable to have this, probably just a small thing never bothered to add. D10912 could use it, the following comment can be addressed now too: https://developer.blender.org/diffusion/B/browse/master/source/blender/editors/space_nla/nla_buttons.c$583-586