While there are many extensions that *claim* to allow right click/copy, this is the only one I've found that actually works every time.

Good, small, fast, works)
But if you enable this extension, it works everywhere. It shouldn't be like this. It should only work on the site where you enabled it. If the user has gone to another site or another tab, then you need to enable it again.
See how Allow Right-Click works.
I'll install it again when it's fixed.
Also, all your extensions should be published on Github.