Make middle mouse button (paste) load URL in Firefox
Problem
Pasting a URL (middle-mouse button) into a Firefox browser window or tab does
not cause the page to be opened.
Keywords
Firefox, middle-mouse button, paste, URL, tab, open, load.
Solution
Open about:config (by writing it in the location
bar) and set middlemouse.contentLoadURL to true. Also check out Making Firefox
Handle Multiline Pasted ("Broken") URLs.