I no longer need this issue solved as I have replaced Ubuntu with a different OS (nothing wrong with Ubuntu, just fancied a change). I reinstalled Ubuntu into a virtual machine and thunderbird began appearing. I did uninstall Thunderbird and reinstall it, so there maybe a chance that a dependency was not satisfied or whatnot.
I know I keep seeming to have a problem with every distribution, but this time I have no idea... Again, as to why this is occurring!
If I search for Thunderbird in the home and applications sections of the dash I get no results, whether it is installed or not. In fact, it doesn't even appear as a store result! I checked /usr/share/applications and lo and behold... Thunderbird is there! In fact, typing 'thunderbird' in terminal opens it!
This is also the case with the messaging applet or whatever it is called (envelope in the notification area). It has the permission to appear in that menu according to dconf-editor, alas it decides not to.
Does anyone have any idea what could possibly cause this? I am using Ubuntu 13.04, and I will provide further information if needed. This is not essential but it is one of those small problems that bugs you to find a fix for. I'm not sure what part of the desktop file if any could cause this problem. Any help would be appreciated! And maybe I might stop breaking it soon.
(No idea if this helps or not but I did install Thunar and use that as my default file application thing, although problem occurred before installing that).
EDIT: My thunderbird.desktop file if that helps at all, considering the dash and mmu both use this to discover it. Translations have been trimmed.
[Desktop Entry] Encoding=UTF-8 Name=Thunderbird Mail Comment=Send and receive mail with Thunderbird GenericName=Mail Client Keywords=Email;E-mail;Newsgroup;Feed;RSS Exec=thunderbird %u Terminal=false X-MultipleArgs=false Type=Application Icon=thunderbird Categories=Application;Network;Email; MimeType=x-scheme-handler/mailto;application/x-xpinstall; StartupNotify=true Actions=Compose;Contacts [Desktop Action Compose] Name=Compose New Message Exec=thunderbird -compose OnlyShowIn=Messaging Menu;Unity; [Desktop Action Contacts] Name=Contacts Exec=thunderbird -addressbook OnlyShowIn=Messaging Menu;Unity;
And if any further help, this is what appears when I open Thunderbird via terminal.
(process:2739): GLib-CRITICAL **: g_slice_set_config: assertion `sys_page_size == 0' failed ** (thunderbird:2739): WARNING **: could not find the desktop file for 'thunderbird.desktop' (thunderbird:2739): GLib-GObject-WARNING **: /build/buildd/glib2.0-2.36.0/./gobject/gsignal.c:3429: signal name `selection_changed' is invalid for instance `0x7f9818072190' of type `MaiAtkType3