The upload options menu (the one that opens when you click on an uploaded image) was missing from my site on firefox. After some tedious troubleshooting, my troubles finally paid off. I found out that the menu was being blocked by my adblocker.
If you're using the AdBlock list from http://www.mozilla.org/support/firefox/adblock (great stuff, btw) in firefox, it *will* block this menu. Delete the line
from userContent.css (under firefox profile folder), and everything will work.
Hopefully this post will be of use to someone out there.
On a side note to the devs, it might be prudent to change the name of that div. 'Popup' seems like something that is blocked by default in many installations.