Sticky Pinned Tab maintains a tab's pinned property when moved between windows. This brings a feature found in Chromium-based browsers (Chrome, Edge, Opera, etc.) to Firefox users.
Moving a pinned tab between Firefox windows causes it to be unpinned. On researching possible solutions I found bug 1505014 which won't be fixed. This extension fixes that bug.
Go to https://addons.mozilla.org/addon/sticky-pinned-tab/ and press the Add to Firefox button.
- Clone the repository to a folder on your hard drive.
- Open Firefox
- Enter "about:debugging" in the URL bar
- Click "This Firefox"
- Click "Load Temporary Add-on"
- Open the cloned repository folder and select any file inside the directory (e.g. manifest.json).