While setting up my new system (Linux Mint 17.3 XFCE / Mintbuntu), I discovered this nasty bug with the Old Location Bar extension, which had "moz-action:" and some JS garbage always appearing in the search dropdown, whenever I was typing something into the location / address bar.
Found a quick in the review section of the oldbar extension. Works both with oldbar and Old Location Bar extension. Should work with others as well (test yourself though) ;)
- Search for
- Set it to FALSE (double click normally does the trick)
- and tadaa: nasty is gone! ;)