A right click "Open Containing Folder" on Downloads box or opening some icons on unity launcher will use app other than nautilus because the default in mimeapps.list is set to nautilus-folder-handler.desktop

[Doug McMahon]

Binary package hint: nautilus
There are now 2 sections created in mimeapps - [Added Associations] and [Default Applications]
As soon as someone opens a folder with an app other than nautilus from the r.click 'open with other application' 2 inode/directory= lines will be created, one in each section

In the [Default Applications] section the inode/directory= is being set to nautilus-folder-handler.desktop which no longer exists
So in the instances mentioned here (below), the 1st listed in the [Added Associations] sections is being incorrectly used

(as mentioned in my final comment editing the line in the default section to nautilus.desktop resolves (or put back nautilus-folder-handler.desktop

Ex.
[Added Associations]
inode/directory=vlc.desktop;

[Default Applications]
inode/directory=nautilus-folder-handler.desktop

When doing the r. click, ect. on the Downloads box in firefox vlc will be opened

(there is a gnome shell extension (places dropdown) that does the exact same thing, the dev seems to feel it conforms to specs, irregardless this behavior is wrong here and there.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: firefox 5.0~b3+build1+nobinonly-0ubuntu1
ProcVersionSignature: Ubuntu 2.6.38-9.43lp760131v201106060906-generic 2.6.38.7
Uname: Linux 2.6.38-9-generic i686
NonfreeKernelModules: nvidia
Architecture: i386
Date: Fri Jun 10 08:22:06 2011
FirefoxPackages:
 firefox 5.0~b3+build1+nobinonly-0ubuntu1
 flashplugin-installer N/A
 adobe-flashplugin 10.3.181.14-0natty1
 icedtea-plugin N/A
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release i386 (20110427.1)
ProcEnviron:
 LANGUAGE=en_US:en
 PATH=(custom, no user)
 LANG=en_US.utf8
 LC_MESSAGES=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: firefox
UpgradeStatus: No upgrade log present (probably fresh install)

[Doug McMahon (mc3man)]

here's that bug report
https://bugzilla.gnome.org/show_bug.cgi?id=652219

[Robert Roth (evfool)]

This might be related to bug #667071, which has been reported many times by users having different applications opening when clicking the Places menu items.
---
Ubuntu Bug Squad volunteer triager
http://wiki.ubuntu.com/BugSquad

[Doug McMahon (mc3man)]

Robert Roth wrote
>This might be related ...
Fortunately that has been resolved and fix released in nautilus 2.3X (natty, maverick, lucid
This is some new behaviour in nautilus 3, though certainly on a much smaller, less likely to occur scale

[Doug McMahon (mc3man)]

Initially thought this was just limited to the firefox and a nautilus extension. It also will affect removable media like usb drives and mounted internal drives
While the user can reset back to "nautilus.desktop" by choosing 'Files' from the open with other application context menu this again is going to cause confusion among users.

If the initial list was created like this and any additional associations append to the line than no issues would arise
[Added Associations]
inode/directory=nautilus.desktop;vlc.desktop;

[Default Applications]
inode/directory=nautilus-folder-handler.desktop

Noting that in the added section it must be nautilus.desktop;, not nautilus-folder-handler.desktop;
Otherwise the 4 actions seen so far would need to be adjusted to use the [Default Applications] instead.

[Doug McMahon (mc3man)]

You can also add the trash icon in the unity launcher to the list of things that will use the first listed .desktop in this section/line of mimeapps.list
[Added Associations]
inode/directory=

[Doug McMahon (mc3man)]

The issue is caused because when mimapps.list is created the inode/directory= line in the [Default Applications] section is using -
nautilus-folder-handler.desktop

This desktop is not in the current nautilus package.
Changing the line to one that is installed resolves all issues, ie., nautilus.desktop or nautilus-home.desktop