I am using the editArea library and jquery to do what i need...
http://www.cdolivet.com/index.php?page=editArea&sess=2b8243f679e0d472397bfa959e1d3841
so
You need search within the inner document of the iframe, in order to get the textarea element:
var textarea = $('textarea', $('iframe').get(0).contentWindow.document);
textarea.keydown(function (e){
var number = 17;
var code = (e.keyCode ? e.keyCode : e.which);
if(code == number){
//do something...
alert('Done...');
}
});