This simple add-on allows users to drag:

• texts: search in foreground/background tabs
• links: open in foreground/background tabs
• images: open in foreground/background tabs
• customize the search engine
• disable fire-drag on some websites

PS: Need to reload webpages after the installation

source code: https://github.com/erictsangx/fire-drag

link: https://addons.mozilla.org/en-US/firefox/addon/fire-drag