If I have Firefox Nightly x64 opened and click on a URL link contained in a Thunderbird email, I receive a message warning that states that FF is running and need to close before I can open the selected URL link. See attached image.
I don't really want another FF session opened. What I would like is for the URL link I clicked on the email to open in a new tab (or on existing tab for all that matters).
Is that possible? Is there a setting I can toggle?