Thanks for the feedback. Can you provide any more details about the problem you are facing so that it can be fixed ?

EDIT:
- The intention of this extension is to support the use-case of those users who open and eventually close a lot of tabs while working with mouse
- Double right click is a simple and unused gesture, hence it fits well with the target use-case of this extension
- The context menu shows up because that happens as soon as the first click is registered. Apart from that, it is not possible to control the native context menu
- You mentioned "Page contents often interfere with the functionality of the right-click". I do not see how that affects the purpose of this extension
- You mentioned "Something that works with Firefox tabs would be ideal". Assuming that you are talking about the tab header:
a). Apparently it is not supported in the new WebExtensions architecture used by Firefox
b). The user would still need to move the mouse up to the tab header. While the purpose of this extension is to avoid the need of moving mouse at all for closing the tab :-)