[boost] [containers] Are there flat_map/set and stable_vector proposals at work?

All is in the title: I would like to know if flat_map, flat_set and stable_vector have been proposed for inclusion in the C++ standard library, or if there are works going on to write such a proposal. I find that I use a bit more flat associative containers than tree-based standard associative containers in all my recent projects, and I think that having option in the standard to choose one or the other would be very useful for a lot of devs.