How to override headers in geckoFX?

Question

I am trying to use this method:

GeckoMIMEInputStream postdata = new GeckoMIMEInputStream();
postdata.AddHeader("Accept-Language", "ru,en-us;q=0.7,en;q=0.3");
browser.Navigate(someurl, flags, referer, postData);

but it adds "ru,en-us;q=0.7,en;q=0.3" to already existing "Accept-Language" string! How to override?

Answer 1

i found it, to change accept_languages:

GeckoPreferences.User["intl.accept_languages"] = "ru";