Comment 12 for bug 592492

I disagree that this is a duplicate of bug #410307, since in my case left-clicks always worked just fine. Furthermore, it's not just that right-clicks were ignored; they actually hung Firefox (sometimes just that window, sometimes the entire application). Occasionally closing the affected window would work and other windows would respond normally, but usually the whole application hung.

The fix mentioned at https://forums.addons.mozilla.org/viewtopic.php?f=26&t=1160 did work around the problem for me, however.