I'm unable to make Thunderbird open the default browser.

In the browser preferences, Chromium is selected as the default browser. It's also selected in "Default Applications" in System Settings.

In Thunderbird, I read "Chrome (Default)" which is wrong on all levels:

1. Chrome itself complains that it's not the default browser when I click a link inside Thunderbird.

2. In all other places, that I could find, Chromium is the default

Here is what I tried:

1. I used update-alternatives --config x-www-browser to select chromium-browser as well (see How do I change the default browser?).

2. And even when I select a different browser from the list in the Thunderbird preferences, it still opens Chrome.

My current solution is to create a link from /usr/bin/google-chrome to chromium-browser.

How can I force Thunderbird to use the browser I want???

EDIT I also updated gnome-www-browser (update-alternatives --config gnome-www-browser) after feedback from roadmr but that didn't help. At least sensible-browser opens Chromium, now, but Thunderbird is stubborn.