Stopped working for me. Keeps searching but no results at all.

Regular expression doesn't work at all. I would've given this five stars if it worked.
(string1|string2)/i is what I used.

Windows 10, latest Firefox

Thank You for this add-on!
I think, it's the best add-on for search of multiple tabs on Firefox 59.
Drawbacks I found:
* Stops working sometimes. Work around: Save all tabs with "OneTab", restart Firefox, open saved tabs again.
* When using multiple windows with multiple tabs, and when "Search Multi Tabs" finds a hit in another window, and when clicking on this hit, "Search Multi Tabs" does not switch to this window.

I'm using:
* Windows 8.1 64-Bit
* FF 59.0.1 (64-Bit)
* Latest version of "Search Multi Tabs" (as of 2018-03-18)