Drop image

I can drug any image from the page an drop it into my editor and it appear in editor. Is it possible prevent dropping image?
I tryed handle events, but there are notinng event when I drop image

var ed = $('#composer').ckeditor();
var editor = ed.ckeditorGet();
editor.on("instanceReady", function (ev){
       evs = editor._.events;
        for (i in evs){
            console.log(evs[i].name);
            editor.on(evs[i].name, function (ev){console.log(ev);});
        }
});

Maybe I do something wrong?
Sorry my English