Middle-click in Firefox browser window calls up Listary

Hello. I love Listary, but when I middle-click in a Firefox browser window (NOT a Firefox dialogue box), Listary pops up and the Firefox middle-click functions (auto-scroll and - on a link - open in new tab) don’t work. These functions are important to me. To me this is a bug, because Listary doesn’t do this in any other application. Is there a way I can stop Listary from doing this?

Go to Options -> Keyboard and Mouse -> Mouse -> untick Middle-click to activate Listary

I want Listary to pop up when I middle-click. But ONLY in a dialogue box. But it’s doing it in the main application window of Firefox. That can’t be by design. It has to be a bug.