If you add this to your favorites and click on it when you are at a page that doesn't allow right clicking, it enables right click again:
java script:x=document.getElementsByTagName('*');for (n=0;n<x.length;n++){x[n].setAttribute('oncontextmenu','return true;');}document.oncontextmenu='return true;';void 0;
Or, you can paste this into the address bar of the site that doesn't allow right clicking and you can enable it.
Note: It might not work with sites that put popup warnings after the right clicks.