Its page rendering appears much improved. But a new problem: while all the fonts at this forum are fine, any text typed into the google.com search dialog, as well as "secondary" text in (about a third of sites are affected) some news sites, etc (past the headline), are in a almost-unreadable cursive (handwriting) script. I haven't found where that is set in the fonts selection, the .Xdefaults, etc etc. Maybe unique to this machine somewhere; even trying to search in "opera:config", almost all the text on THAT page is in the near-unreadable type... (unless switching author mode >> user mode maybe). Nor did the "Managing author mode" customization dialog present a clue...
/edit.........../
Gave up. Earlier 11-version from backups. Clunkier from before the upgrade (some customizations lost probably), but I am used to it already.
/edit2..........
Trial and error in Menu >> Appearance, and everything is peachy in the former version once more.