CSInterface keydown addEventListener

Hello,

In Adobe Html 5 Cep panels, keyboard events are not detected. According to  CSInterface https://github.com/Adobe-CEP/CEP-Resources/wiki/CEP-6-HTML-Extension-Cookbook-for-CC-2015, 'CSInterface.prototype.addEventListener' function is the key, but I can't make it work in AE Cep panel. Here it is the code:

var csInterface = new CSInterface();

csInterface.prototype.addEventListener('keydown',function(e){

  alert("keydown detected")

});