I can’t seem to find any reference to a shortcut or theme component to Save a Topic Post without closing (and then having to re-open) the Composer.
Is anyone aware of any existing way to do this?
I can Tab-Enter (conveniently) to save a composition in progress.
Are you thinking of drafts?
No, thank you, I am aware of that 
. I guess I’m a bit old-school mistrusting. I have lost edits, most often when I’m composing on my iPhone in the morning still in bed.
You are not alone in your drafts edit struggles. I too lose many… I use my drafts and notes pm link for important stuff on Meta. Otherwise it’s my admin folders.
How can an ordinary user convert a pm to a topic?
copy and paste 
I just meant using the pm to save stuff like a note pad or drafts.
Exacly my point. That is far away user friendly solution.
Well, I’ve told - if I’m remembering right - more than one draft as a new topic is technically impossible on Discourse. But this kind of solutions are something else than acceptable one.
Ctrl-Enter Saves and Closes. How difficult would it be to add a Composer Shortcut for Save and Keep Open, or Save and Re-Open?
Ctrl-S
How that save is different than automatic save as a draft?
I don’t know the technical answer to that. But I think that the ability to save on command would help me to prevent losing my edits.