> But the completion hint is totally weird. If I type just one "o"
> above, it works as it should.

I don't see much difference between the "oo" case you've shown and the
"o" case, so I don't see why one "works as it should" while the other
"is totally weird".

Can you explain a bit more?

You're right, there is no difference. I must have been drunk, or something... ;)

Still, regardless of I type "o" or "oo", I do not see the full buffer names in the list of hits. However, if I type "e" instead I see all buffer names that match "e", including foo.el and foo.template.

Does this scenario work well for you?

/Mathias