Vlad For changing right click options, I think user.css can be changed (I have never tried this and don't know much about it).
However, for advanced preferences, there is about:config. I have attached screenshots below.
For an idea of the kind of customization allowable, refer to https://github.com/arkenfox/user.js/blob/master/user.js
joystmp Hm not sure how those screenshots address this:
Not sure how would UI for this look like, because context-menu is context dependent. It is different if you click anywhere on page, on a link, select some text, on an image... plus it changes based on installed extensions.
Meaning that existence and position of elements in the context menu, depends a lot on the context where the menu is triggered. So it is unclear how would an UI to allow setting this would look like.
We are still looking for a suggestion what an UI for making these adjustments for handling different context menu situations.
Hey Vlad, don't you like the Path Finder interface posted above?
On the left are all the options. Right: activated options.
Just move the options from left to right and top to bottom.
Younger_Me The thing is, context menus look different depending on what you're clicking, as per the word "context" in the name. When clicking an image, text, url, or video, different options show up.
eirk Of course. This is obviously also the case for path finder 
Younger_Me Not that I do not like it, but trying to understand how do we fit yet another niche feature while we have 2000 open bug reports. My recommendation is to simplify the ask to the minimum viable. Recreating some kind of new UI takes a lot of time. I wish we could do everything you recommend, we simply need to balance available resources.
Vlad of course I post my ideas, and if you like them, you can put them wherever you like on the waiting list 
