The post composer will only be closed once the message is sent, so if there is an network error the post you wrote is not lost and you can try posting it again. (Joshua Goins, Link 1, Link 2) Other ways to interact with a post are now available in an overflow menu for posts adding actions like a “Copy link to post” feature (Joshua Goins, Link), a bookmark feature (Joshua Goins, Link) and the previously mentioned edit feature (Joshua Goins, Link)