Yesterday I was typing my post, and blogger ate it! Well, almost. I had to stop my typing so I saved the text as draft. Usually I copy the text from the browser into some local scratch file before submitting it. Yesterday I forgot to do that. When I returned to continue editing the draft - no text was there! Today I tried to make a test post, with the same result. All of this I did using the Opera browser.
So I tried to publish something using Firefox - and it worked. It wouldn't be so surprising if I had not published 3-4 posts previously with Opera.
The conclusion - Google/Blogger made some changes in the meantime, and they've caused Opera to be unusable for publishing blogs! Time to contact them, if possible.