iPad iframe scrollbar problem

I have a problem on iPad with this html definition:

<iframe id="DOMWindowIframe" name="DOMWindowIframe" src="'+settings.windowSourceURL+'" class="domWindowIfr开发者_运维技巧ame" frameBorder="no" scrolling="yes">
</iframe>

The problem is that the scroll bar is not visible on iPad. Is it possibile to fix this issue?

Kind regards Massimo

iPad doesn't display a scroll bar. The iframe should be scrollable using a two fingered drag.

And now, the two finger draging function is removed in iframe