Drag and drop files in Firefox (v10)

I am trying to drag and drop a file in firefox and I am starting to do baby steps. Right now I'm just trying to drag and drop some files into dropzone and get a list of deleted files. At the moment, I do not want to do anything with the files.

When I drag a file (in this case, the image, but the same thing happens regardless of the file type) from the finder to dropzone, I can see the dragenter and dragexit shooting. When I drop the file into dropzone, the drop event does not fire. Instead, the browser opens its own image (for example, the address shows the file: //path/to/my/image.png).

My javascript looks like this:

  dropbox = document.getElementById("standard_file_dropzone");

  dropbox.addEventListener("dragenter", function(){console.log('standard enter');}, false);
  dropbox.addEventListener("dragexit", function(){console.log('standard exit');}, false);
  dropbox.addEventListener("dragover", $.noop, false);
  dropbox.addEventListener("drop", function ( event ) {
                                     console.log('standard dropped');
                                     event.stopPropagation();
                                     event.preventDefault();

                                     if(( typeof event.dataTransfer.files !== 'undefined' ) &&
                                        ( event.dataTransfer.files.length > 0 )) {
                                       console.dir( event.dataTransfer.files );

                                     }
                                     return false;
                                   }, false);

My HTML looks like this:

    <div id="standard_file_dropzone" style="height:150px; width:150px; border:solid;">
      Standard Drop Files Here
    </div>

, ? , ( ) . dragenter/exit , drop? ?

, Chrome, , , Firefox.

Thnx, Christoph