In latest KUbuntu live image, that envioronment variable is set out-of- box, and so xdg-utils correctly recognize KDE5, in particular, xdg-open uses kde-open5. I think therefore the bug may be considered fixed.
** Changed in: xdg-utils (Ubuntu) Status: Confirmed => Fix Released -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/545044 Title: Xdg-open should use kde-open instead of kfmclient To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xdg-utils/+bug/545044/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs