Об этом дополнении
Quick Access to Notion in a new tab with just one click on a simple, stylish icon button on your Spaces toolbar.
Source code;
https://github.com/tdmrhn/Thunderbird-Quick-Access-Buttons/
Commit by;
https://github.com/borangoher
Source code;
https://github.com/tdmrhn/Thunderbird-Quick-Access-Buttons/
Commit by;
https://github.com/borangoher