Simple way to change Firefox Useragent

[Geograph]

Simple changing Firefox User-Agent using "FF.au3" without manual edit "prefs.js"

#Include <FF.au3>

If _FFConnect() Then
   ;Default User-Agent
   _FFOpenURL("http://useragentstring.com/")
   Sleep(5000)
   
   ;Set new User-Agent
   FFSetUserAgent("Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/48.0.2564.116 Safari/537.36")
   _FFOpenURL("http://useragentstring.com/")
   Sleep(5000)
   
   ;Reset to default User-Agent
   FFResetUserAgent()
   _FFOpenURL("http://useragentstring.com/")
   Sleep(5000)
   
   _FFDisConnect()
Else
   MsgBox(0, "", "Can't connect to FireFox!")
EndIf

Func FFResetUserAgent()
   _FFCmd("Components.classes['@mozilla.org/preferences-service;1'].getService(Components.interfaces.nsIPrefService).getBranch('general.useragent.').clearUserPref('override');")
EndFunc

Func FFSetUserAgent($useragent)
   FFResetUserAgent()
   _FFCmd("Ci=Components.interfaces;Cc=Components.classes;string=Cc['@mozilla.org/supports-string;1'].createInstance(Ci.nsISupportsString);string.data='" & $useragent & "';Cc['@mozilla.org/preferences-service;1'].getService(Ci.nsIPrefService).getBranch('general.useragent.').setComplexValue('override',Ci.nsISupportsString,string);")
EndFunc