During drag and drop, can't drop onto text field

```
When dragging a new element onto the stage, drop is not allowed when your mouse 
pointer is over a text field contained within an existing element on the stage. 
 Dropping anywhere else on top of the existing element is fine, and correctly 
inserts above or below the existing element.
```

Original issue reported on code.google.com by `garthabr...@gmail.com` on 24 Oct 2011 at 2:42
