Sorry, I was wrong. The counter is ok in IE. Instead, it fires `drop` event while editor autoscrolling.
Firefox issue is probably my instance only issue )
But still, what do you think about this code:
```javascript
var toElement = document.elementFromPoint(e.pageX, e.pageY);
if (!toElement || !editor.container.contains(toElement)) {
    ...
}
```
This works fine everywhere except Opera (it fails when an editor edge is located at a window edge).