Works ok but causes random crashes when used with Webpage Sidebar extension.

This was great when it worked, and sometimes it still works. But it's very unreliable and often just fails to work.

Можно использовать не во всех полях текстового ввода, но строго в определенных. В моем случае я получил "The selected field is not valid for Markdown rendering. Please use a rich editor". Mozilla Firefox 89.0b7 (64-bit).