Reading Firefox about:config settings via Javascript

[Yamagami]

Hi all,
I've created a nifty context menu script that works great except for
one caveat: If the user has set his firefox configuration to disable
context menus, via either Options->Content->Advanced or about:config-

dom.event.contextmenu.enabled=false, then the browser's context menu

is displayed on top of my context menu.

I'd like to disable my context menu if that is the case, but I can't
find ANY way to read the settings in about:config via javascript! I've
found nice tutorials on how to do it as extensions to firefox, but its
out of scope... I just need to check if the user has this option set
to false in order to prevent my script from running....

The script is available at: http://www.harelmalka.com?p=60
Demo is at: http://www.harelmalka.com/rightcontext

Is there a way to do it?

Thanks in advance,
Harel Malka