If I had to guess, I'd say blame Opera (probably silently installed an update that broke stuff?). It's my favourite browser, but a real bitch
to get to properly integrate with other programs. I have a wrapper script that launches it with "opera -nomail -newtab $(url)", maybe try it this way? Can't remember exactly
why I put the "-newtab" in there however.
If you don't want to use a wrapper, setting ExternalBrowser in the ini file's "Advanced" section might
work too, haven't tried it though, so no guarantees.