add: if (isScrollbar(target)) { return; } 
context:   function browserHandleMiddleClick(event)  {    var target = event.target;    if (pref.GetBoolPref("middlemouse.openNewWindow"))    {      var href = enclosingLink(target);      if (href != "")      {        openNewWindowWith(href);        event.preventBubble();        return;      }    }    if (pref.GetBoolPref("middlemouse.paste"))    {      var tagName = target.tagName;      if (tagName) tagName = tagName.toLowerCase();      var type = target.type;      if (type) type = type.toLowerCase();      if (!((tagName == "input"             && (type == "" || type == "text" || type == "password"))            || tagName == "textarea"))      {        var url = readFromClipboard();        //dump ("Loading URL on clipboard: '" + url + "'; length = " + url.length + "\n");        if (url.length > 0)        {          var urlBar = document.getElementById("urlbar");          urlBar.value = url;          BrowserLoadURL();          event.preventBubble();        }      }    }  }
meta: 10234	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/10234/7190bdece27cb0c8481e23d5c07e202261be097a/navigator.js/buggy/suite/browser/navigator.js