Okay, it's spread to this page; trying again to point out that posting and editing seem to have gone nondeterministic. No error messages, just loads the page afresh with no sign of my post or edit.
Oo! New bit of info: I deleted my cookies and tried to edit this. And it appeared to work. And then I tried to edit the edit to correct a spelling mistake, and the entire passage added in the first edit is missing from the editor! Now let's see whether this saves... 
