Description of problem:
We have several applications we provide from a network volume.  We defined an alternate AppDir and DirectoryDir in a file in /etc/xdg/menus/applications-merged/.  It looks something like this:

 cat /etc/xdg/menus/applications-merged/caen.menu 
<!DOCTYPE Menu PUBLIC "-//freedesktop//DTD Menu 1.0//EN"
 "http://www.freedesktop.org/standards/menu-spec/1.0/menu.dtd">

<Menu>

  <Name>Applications</Name>
  
  <!-- Add caen applications to menus -->
  <AppDir>/usr/caen/misc/menus/applications</AppDir>
  <DirectoryDir>/usr/caen/misc/menus/directories</DirectoryDir>

<Menu>
<Name>MCAD ECAD MCAE Tools</Name>
<Directory>MCAD.directory</Directory>
<Include>
<And>
<Category>MCAD</Category>
</And>
</Include>
</Menu>
<Menu>
<Name>Engineering Applications</Name>
<Directory>ENGIN.directory</Directory>
<Include>
<And>
<Category>ENGIN</Category>
</And>
</Include>
</Menu>
  
</Menu> <!-- End Applications -->


We define several directories and applications in /usr/caen/misc/menus.  If we run Cinnamon Desktop from EPEL, they show up fine, but if we run Gnome Classic, when you click on the menu, and hover over the "MCAD ECAD MCAE Tools" or the "Engineering Applications" menu, it doesn't highlight it nor does it open the submenu.

We discovered if we updated one of our .desktop files to use one of the Categories used by one of the built-in menus, that menu entry would also not highlight and show the submenu.

I looked at the logs, and discovered that when I hovered over a menu that had desktop definitions from our alternate AppDir, this error appeared in the user's session logs:


Jul 06 10:32:43 caen-z240 gnome-session[8652]: (gnome-shell:8910): Gjs-WARNING **: JS ERROR: TypeError: app is null
Jul 06 10:32:43 caen-z240 gnome-session[8652]: ApplicationMenuItem<._init@/usr/share/gnome-shell/extensions/apps-menu.github.com/extension.js:62
Jul 06 10:32:43 caen-z240 gnome-session[8652]: wrapper@resource:///org/gnome/gjs/modules/lang.js:169
Jul 06 10:32:43 caen-z240 gnome-session[8652]: _Base.prototype._construct@resource:///org/gnome/gjs/modules/lang.js:110
Jul 06 10:32:43 caen-z240 gnome-session[8652]: Class.prototype._construct/newClass@resource:///org/gnome/gjs/modules/lang.js:204
Jul 06 10:32:43 caen-z240 gnome-session[8652]: ApplicationsButton<._displayButtons@/usr/share/gnome-shell/extensions/apps-menu.github.com/extension.js:
Jul 06 10:32:43 caen-z240 gnome-session[8652]: wrapper@resource:///org/gnome/gjs/modules/lang.js:169
Jul 06 10:32:43 caen-z240 gnome-session[8652]: ApplicationsButton<.selectCategory@/usr/share/gnome-shell/extensions/apps-menu.github.com/extension.js:5
Jul 06 10:32:43 caen-z240 gnome-session[8652]: wrapper@resource:///org/gnome/gjs/modules/lang.js:169
Jul 06 10:32:43 caen-z240 gnome-session[8652]: CategoryMenuItem<.setActive@/usr/share/gnome-shell/extensions/apps-menu.github.com/extension.js:204
Jul 06 10:32:43 caen-z240 gnome-session[8652]: wrapper@resource:///org/gnome/gjs/modules/lang.js:169
Jul 06 10:32:43 caen-z240 gnome-session[8652]: PopupBaseMenuItem<._onHoverChanged@resource:///org/gnome/shell/ui/popupMenu.js:149
Jul 06 10:32:43 caen-z240 gnome-session[8652]: wrapper@resource:///org/gnome/gjs/modules/lang.js:169
Jul 06 10:32:43 caen-z240 gnome-session[8652]: CategoryMenuItem<._onMotionEvent@/usr/share/gnome-shell/extensions/apps-menu.github.com/extension.js:190
Jul 06 10:32:43 caen-z240 gnome-session[8652]: wrapper@resource:///org/gnome/gjs/modules/lang.js:169

Looking in /usr/share/gnome-shell/extensions/apps-menu.github.com/extension.js, I believe the failure is in the _loadCategory function, on line 424:

   424                  let app = appSys.lookup_app(entry.get_desktop_file_id());
   425                  if (appInfo.should_show()) {
   426                      let menu_id = dir.get_menu_id();
   427                      this.applicationsByCategory[categoryId].push(app);
   428                  }

What is happening is that appSys.lookup_app() is returning null, and JS just stops and logs the above error.  I made a minor modification to the extension.js file so it looks like this:

   424                  let app = appSys.lookup_app(entry.get_desktop_file_id());
   425                  if (app == null) {
   426                      global.log("null app: "+ entry.get_desktop_file_id())
   427                  } else if (appInfo.should_show()) {
   428                      let menu_id = dir.get_menu_id();
   429                      this.applicationsByCategory[categoryId].push(app);
   430                  }

and now when I log in, I get a bunch of log entries in the session log that look like this:

Jul 06 11:16:32 caen-z240 gnome-session[13068]: Gjs-Message: JS LOG: null app: ENGIN-ChemkinProv17.0.desktop
Jul 06 11:16:32 caen-z240 gnome-session[13068]: Gjs-Message: JS LOG: null app: MCAD-ABAQUS-CAE2016.desktop
Jul 06 11:16:32 caen-z240 gnome-session[13068]: Gjs-Message: JS LOG: null app: MCAD-ABAQUS-DOC2016.desktop

Now the Application menu doesn't generate any errors in the logs, but of course, my menus don't appear.  I was going to file a bug against the upstream Gnome project, but I ran across this bug in their BZ:  https://bugzilla.gnome.org/show_bug.cgi?id=762206

This makes me think that the Gnome3 developers don't intend to support alternate AppDirs.  Sadly, the existing XDG spec for menu definitions continues to have the definition, and other desktop environments are fine using them.  (See the latest spec to see it is still defined: https://specifications.freedesktop.org/menu-spec/menu-spec-latest.html)

In the end, I made a symlink /usr/local/share/applications to point at our alternative AppDir, since we weren't using /usr/local/share/applications already, but this is obviously a limited solution, it breaks the 'filesystem' package's RPM validation check:

# rpm -V filesystem
.....UG..    /usr/local/share/applications

So we have to manage that symlink externally to RPM now.

It would be great if this package could be updated with fixed code to at least better handle failures.  It would be great if we could get back the functionality to be able to use alternative AppDirs.


Version-Release number of selected component (if applicable):
gnome-shell-extension-apps-menu-3.14.4-13.el7.noarch

How reproducible:
Always

Steps to Reproduce:
1. Define an AppDir in a merged file from /etc/xdg/menus/applications-merged/
2. Define a desktop entry that has a Category that would show up in any of the defined menus
3. Try to select that menu from the Applications menu

Actual results:
Application Menu will show menu but not highlight it when you hover over it, and will not show any valid entries, even if they are from standard locations provided by packages.

Expected results:
Additional menu entries will appear and be selectable.

Additional info: