Since Firefox 13, it was not possible to use the meta key as a modifier on Linux. According to https://bugzilla.mozilla.org/show_bug.cgi?id=751749, this was fixed in Firefox 17. I am trying to find a xmodmap setting that does the job in order to use the menu key plus some nearby keys (forward and backward on a Thinkpad keyboard) to the "Next, please" command of the Nextplease addon using keyconfig. - I am using KDE 4.10 and Firefox 22. Mapping the keycode of the menu key (135) to the Keysym Meta_R and adding the Mod4 modifier Meta_R only leads to keyconfig detecting "Meta+VK_META", any simultaneously pressed second key is not detected at all. I would be really thankful if you could help me to use my old keyconfigs again.