var ps = Components. classes ["@mozilla.org/preferences-service;1"]. getService (Components. interfaces. nsIPrefService). getBranch ("general.");
    ps. setCharPref ("useragent.override", "reset");

this.PS = Components.classes['@mozilla.org/preferences-service;1'] .getService(Components.interfaces.nsIPrefBranch);
this.PS.clearUserPref("general.useragent.override");
this.image=
'data:image/gif;base64,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';


var меню =
<menupopup xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
       oncommand="this.parentNode.сменитьЮзерагент(event)">
          <menuitem type="radio" value="reset" label="Default User-Agent"/>
          <menuseparator/>
          <menuitem type="radio" value="Mozilla/5.0 (Windows; U; Windows NT 5.1; ru; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3 YB/3.5.1" label="FF 3.6.3+yandexbar"/>
    <menuitem type="radio" value="Mozilla/5.0 (Windows; U; Windows NT 5.1; ru; rv:1.9.1.4) Gecko/20091016 Firefox/1.5.4" label="firefox 1.5.4"/>
    <menuitem type="radio" value="Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)" label="IE-6"/>
    <menuitem type="radio" value="iCab/3.0.2 (Macintosh; U; PPC Mac OS)" label="iCab/Mac"/>
    <menuitem type="radio" value="Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.3) Gecko/20090914 Slackware/13.0_stable Firefox/3.5.3" label="Slackware"/>
    <menuitem type="radio" value="Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10.4; ru; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3" label="Firefox/3.6.3 Mac OS X 10.4"/>
      <menuitem type="radio" value="Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/532.9 (KHTML, like Gecko) Chrome/5.0.307.0 Safari/532.9" label="Chrome/5.0.307.0"/>
</menupopup>;


меню = custombuttonsUtils. makeXML (меню);
меню. childNodes [0]. setAttribute ("checked", "true");
this. orient = "horizontal";
this. type = "menu";
this. appendChild (меню);
this. сменитьЮзерагент = function (событие)
{
    var юзерагент = событие. target. getAttribute ("value");
       var ps = Components. classes ["@mozilla.org/preferences-service;1"]. getService (Components. interfaces. nsIPrefService). getBranch ("general.");
    ps. setCharPref ("useragent.override", юзерагент);
this.PS = Components.classes['@mozilla.org/preferences-service;1'] .getService(Components.interfaces.nsIPrefBranch);
this.pref='general.useragent.override';
var state=this.PS.getCharPref(this.pref);
if (state=="reset") { 
this.PS = Components.classes['@mozilla.org/preferences-service;1'] .getService(Components.interfaces.nsIPrefBranch);
this.pref='general.useragent.override';
var state=this.PS.getCharPref(this.pref);
this.PS = Components.classes['@mozilla.org/preferences-service;1'] .getService(Components.interfaces.nsIPrefBranch);
this.PS.clearUserPref("general.useragent.override"); 
this.image=
'data:image/gif;base64,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';

 }
 else { this.image=
'data:image/gif;base64,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';

 };
}