Hi there!
I never experienced such problem. What search url do you use in extension settings?

Ok actually found the reason for the issue. There is an interference with another addon. The Firefox Multi-Account Containers addon. When i disable that, it works like a charm. And while messing around with your addon a bit I thought about another featrure request. How about the option to set another default place to open it, beside the mouse location or the screen center. on the lift/ right corner of the page, or maybe simply by coordinates? And can you add a context menu hotkey? Like "S" is for search with google, that would be great :)

I see. It seems that browser overrides "Open in popup window" behavior and reopens url in main window when it's set to be opened in another container... I can't think about any easy fix for such behavior right now. Thanks for sharing.

I'll considering adding these options in the next extension update whenever I get my hands on it.

New "Popup window location" setting was introduced in latest version 0.1.1, which allows to set popup window in top left, top right, bottom left and bottom right corners 👍