The context that I'm personally interested in at the moment is "Link Context" under the "Context Menu" setting. But it seems that other applicable contexts are Selection, Image, Video, Audio.
My particular use case is that while I use Firefox, I want to open some links in a separate browser instance with a different profile. I were using Chrome for that initially and some links I'd open in a specific profile in Firefox with the "Open in Firefox" extension. But unfortunately there's no "Open in Firefox" extension for Firefox, so I'm using this much more generic extension that doesn't have the "Open With Keyboard and Mouse Click Combinations" setting.