Also idezojel

// ==UserScript==
// @name           Hungarian quotesign
// @namespace      Bohocmasni
// @include        *
// kicsereli a ,,-t „-re
// ==/UserScript==

function KeyCheck(e)
{
 if (e.keyCode == 188) 
 { setTimeout(runa,25); }

 if (e.keyCode == 222) 
 { setTimeout(runf,25); }
}

function runa() 
{

 tomb = document.getElementsByTagName('textarea');
 for(i=0; tomb[i]; i++)
 {
  str=tomb[i].value;
  tomb[i].value=str.replace(",,","„");
 }
}

function runf() 
{

 tomb = document.getElementsByTagName('textarea');
 for(i=0; tomb[i]; i++)
 {
  str=tomb[i].value;
  tomb[i].value=str.replace('"','”');
 }
}



window.addEventListener('keydown', KeyCheck, true);