after an update I had some issues with firefox version .
I can no longer open Apex Builder Plugin settings from greasemonkey.
It worked fine yesterday.
I tried to add in about:config, set /i/apex_builder_plugin as described hereabout but no joy
so I changed in default in
vi './Application Support/Firefox/Profiles/llalwlt0.default/gm_scripts/apex_builder_plugin_19/apex_builder_plugin_19.user.js'
and that worked around it.
I will see if I can find out more later, I am a bit busy. 8).