--- a/firefox-devel.rst	Fri May 29 23:05:59 2015 +0300
+++ b/firefox-devel.rst	Sun Jun 07 11:09:41 2015 +0300
@@ -101,6 +101,19 @@
   // Detect deprecated code use.
   user_pref("devtools.errorconsole.deprecation_warnings", true);
 
+Examine ``devtool`` options in ``about:config`` with prefix ``devtools.``::
+
+  user_pref("devtools.debugger.enabled", true);
+  user_pref("devtools.debugger.pause-on-exceptions", true);
+  user_pref("devtools.debugger.auto-pretty-print", true);
+
+  user_pref("devtools.debugger.chrome-debugging-host", "localhost");
+  user_pref("devtools.debugger.chrome-debugging-port", 6080);
+  user_pref("devtools.debugger.ignore-caught-exceptions", true);
+  user_pref("devtools.debugger.remote-enabled, true);
+  user_pref("devtools.debugger.remote-host", "localhost");
+  user_pref("devtools.debugger.remote-port", 6000);
+
 See:
 
   https://developer.mozilla.org/en/Setting_up_extension_development_environment