I can confirm that with xterm 216-0ubuntu1. It looks like xterm doesn't respect dead keys at all. Every dead key is not dead but handled like a normal key instead.
** Changed in: xterm (Ubuntu) Status: Unconfirmed => Confirmed -- keymap not (completely) honored https://launchpad.net/bugs/58689 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs