OK
I thought the problem with first-letter use was just about ADE. I had the feeling :first-letter had been around for ages and did not know it was not EPUB 2 compliant.
Thanks for your answers, so the fruit is not yet ripe. For those who may be interested, I posted a nine minutes video -in French- on the French language forum about a more "classical" method to insert dropcaps (but it's mostly about
writer2xhtml). I will keep this technique for sometime.
https://www.mobileread.com/forums/sho...&postcount=258