This is something that's commonly abused, so I almost always want it to be off, except when I'm using a handful of large webapps that use the feature properly, such as Google Docs. I know there's a universal toggle for this in the Firefox preferences; but is there a way to grant this privilege only to certain domains? Something like a whitelist?
you can try no-script Addone for firefox and allow the script on the few sites you want. You also can enable each script file saparate if you want.
EDIT: If you only want to block the contextmenu itself you can follow these steps:
edit-> preferences -> content -> advanced options of JScript -> set the toggle to "disable or replace context menu"
i know this is an old question, but it's exactly the one i've been trying to find an answer for, and the ones here don't seem to fully satisfy the original question.
It appears to me the only way to regulate just context menu access to specific sites is using Firefox's "hidden" CAPS feature:
It can be tricky to manage the policies, and any time you want to add a new site to the list, you have to edit the user.js file & restart Firefox.
i'm not really a fan of using add-ons to manage built-in features, since i want the policies to be persistent & i see no reason to let Firefox suck even more memory for an add-on i'll rarely utilize once my settings are established.
The only question i have about doing this through CAPS is how to address the actual context menu option.