Can't run Thunar from Firefox

As a workaround, you can add the following to /etc/apparmor.d/local/usr.bin.firefox:

  /usr/bin/Thunar Ux,

Then perform the following:
sudo apparmor_parser -r /etc/apparmor.d/usr.bin.firefox

This bug was fixed in the package apparmor - 2.7.0-0ubuntu1

---------------
apparmor (2.7.0-0ubuntu1) precise; urgency=low

  * New upstream release. Fixes the following:
    - LP: #794974
    - LP: #815883
    - LP: #840973
  * Drop the following patches, included upstream:
    - af_names-generation.patch
    - 0004-adjust-logprof-log-search-order.patch
    - 0005-lp826914.patch
    - 0006-lp838275.patch
    - 0007-fix-introspection-tests.patch
  * Rename 0003-add-debian-integration-to-lighttpd.patch to 0002
  * debian/patches/0003-commits-through-r1882.patch: several bug,
    documentation and performance fixes on our road to AppArmor 2.8
    (LP: #840734, LP: #905412)
  * debian/patches/0004-lp887992.patch: cups-client abstraction should allow
    owner read of @{HOME}/.cups/client.conf and @{HOME}/.cups/lpoptions
    (LP: #887992)
  * update debian/patches/0001-add-chromium-browser.patch for deeper
    directories of /sys/devices/pci (LP: #885833)
  * debian/patches/0005-lp884748.patch: allow kate as text editor in the
    browsers abstraction (LP: #884748)
  * debian/patches/0006-lp870992.patch: abstractions/fonts should allow access
    to ~/.fonts.conf.d (LP: #870992)
  * debian/patches/0007-lp860856.patch: allow read access to sitecustomize.py
    in the python abstraction, which is needed for apport hooks to work in
    python applications (LP: #860856)
  * debian/patches/0008-lp852062.patch: update binaries for transmission
    clients (LP: #852062)
  * debian/patches/0009-lp851977.patch: allow ixr access to exo-open for
    Xubuntu and friends (LP: #851977)
  * debian/patches/0010-lp890894.patch: allow access to Thunar as well as
    thunar in ubuntu-integration abstraction (LP: #890894)
  * debian/patches/0011-lp817956.patch: update usr.sbin.sshd example profile
    (LP: #817956)
  * debian/patches/0012-lp458922.patch: update dovecot deliver profile to
    access various .conf files for dovecot (LP: #458922)
  * debian/patches/0013-lp769148.patch: allow avahi to do dbus introspection
    (LP: #769148)
  * debian/patches/0014-lp904548.patch: fix typo for multiarch line for gconv
    (LP: #904548)
  * debian/patches/0015-lp712584.patch: Nvidia users need access to
    /dev/nvidia* files for various plugins to work right. Since these are all
    focused around multimedia, add the acceses to the multimedia abstraction.
    (LP: #712584)
  * debian/patches/0016-lp562831.patch: allow fireclam plugin to work
    (LP: #562831)
  * debian/patches/0017-lp662906.patch: allow software-center in the ubuntu
    integration browser abstraction (LP: #662906)
  * debian/patches/0018-deny-home-pki-so.patch: update private-files
    abstraction to deny write and link to ~/.pki/nssdb/*so files (LP: #911847)
  * debian/patches/0019-lp899963.patch: add audacity to the
    ubuntu-media-players abstraction (LP: #899963)
  * debian/patches/0020-lp912754a.patch,0021-lp912754b.patch: add p11-kit
    abstraction and add it to the authentication abstraction (LP: #912754)
  * debian/patches/0022-workaround-lp851986.patch: instead of using Ux
    in the ubuntu and launchpad abstractions, use a helper child profile.
    This will help work around the lack of en...