code: private IContainer getActualTarget(IResource mouseTarget) {
  
  		/* if cursor is on a file, return the parent */
  		if (mouseTarget.getType() == IResource.FILE) {
  			return mouseTarget.getParent();
  		}
  		/* otherwise the mouseTarget is the real target */
  		return (IContainer) mouseTarget;
  	}
docs: Returns the actual target of the drop, given the resource under the
  mouse. If the mouse target is a file, then the drop actually occurs in
  its parent. If the drop location is before or after the mouse target and
  feedback is enabled, the target is also the parent.