How do I set Lightning as the default calendar app?

Solution 1:

Thunderbird can be set as default calendar application by opening the file:

$HOME/.local/share/applications/mimeapps.list*

In a text-editor such as GEdit and adding the line text/calendar=thunderbird.desktop to the [Default Applications] section. You may or may not need to add that same line to the [Added Associations] section too.

*To find and open this file, press the button combo Ctrl+H in your home folder, and look for .local, then find the file, right-click it and Open with..., or just double-click. After adding the line, press CTRL+Q, answer YES when asked to save.

See also this comment in the bug report.

Solution 2:

Edit the MIMETYPE line in /usr/share/applications/thuderbird.desktop to read:

MimeType=message/rfc822;x-scheme-handler/mailto;text/calendar;text/x-vcard;

Then run sudo update-desktop-database -q

Now in "Default Applications" you will find Thunderbird in the list of calendar applications.

Source: http://onemoretech.wordpress.com/2014/02/12/thunderbird-as-default-gnome-calendar/

Solution 3:

Calendar Extension for Thunderbird

Install this plug-in by clicking this link: xul-ext-lightning

or open a terminal (e.g. gnome-terminal) and type:

sudo apt-get install xul-ext-lightning

That's all, folks!