ckeditor on focus not working

Question

Just trying to do a simple on focus command with ckeditor and jquery.

var foo = // what can i do here to signal ckeditor?
$(foo).focus(function(){
  $(".class1").hide();
  $(".class2").show();
});

Maybe this is really simple and I'm just overlooking it but any advice or links are greatly appreciated.

Have tried:
CKEditor on focus remove default value
How to listen to basic events in CKEditor?
http://docs.ckeditor.com/#!/api/CKEDITOR.focusManager-method-constructor
http://www.mytechlogy.com/professionals/questions/forum-details/158/how-to-make-focus-in-ckeditor-using-js/?ref=related_posts#.U2EgUv3z3eI
http://ckeditor.com/forums/Support/jquery-click-event-not-working-textarea-ckeditor

Answer 1

Basic idea with CKEditor's events

CKEDITOR.on('instanceCreated', function (event) {
    event.editor.on("focus", function () {  //nothing to do with jQuery, this is CKEDITOR's on
        $(".class1").hide();
        $(".class2").show();
    }
);

or

CKEDITOR.instances["editorID"].on("focus", function(){  //CKEDITOR's ON
    $(".class1").hide();
    $(".class2").show();
} );