Shape 5

I'm using S5 Multibox feature to show help page popup on my article.
It works perfectlty on desktop, android phone or tablet, but on Ipad I can't scroll content box

Hello,

Can you post a URL to this page with the coding applied?

Ok.
http://www.pswi2m.it/cms/index.php/prodotti/software-gestionale-per-professionisti/15-console-telematici  (http://www.pswi2m.it/cms/index.php/prodotti/software-gestionale-per-professionisti/15-console-telematici)
On this page, if you click on "Contattaci" button, you can verify this issue.
You should view a form and after the captcha field there is a submit button labeled "Invia". You can't view this button if you can't scroll inside S5 Box.

Hello,

In the Template Manager under Javascripts you need to increase the value for Max Height to a value that shows the button below.

Multibox Max Height

You might also consider just modifying the padding of the containing cells so there isn't as much space between each input.

Ok, this is the naturally solution to this specific page. But my question is more general. It's possible that  S5 Multibox Addon is not fully compatible with Ipad Tablet?
If I use this box to show, for example, an online help with hundreds lines of text (as I mentioned on first post), increase "Max Height" value isn't a solution. I need scrolling feature (on android tablet and desktop client it works perfectly). 

Hello,

Could you PM me Joomla Super User and FTP access so I can take a closer look at the script on your server?

It's not a good idea. I'm not authorizated to do this.
What script do you want look? S5 Multibox addon is the unmodified version included in Corpway template, downloaded on 19 September 2014.
Take a look on your site at http://www.shape5.com/demo/corpway/index.php/features-mainmenu-47/template-features/multibox-enabled (http://www.shape5.com/demo/corpway/index.php/features-mainmenu-47/template-features/multibox-enabled) and test on Ipad the last "Iframe/HTML Example".

Hello,

I looked into this a bit more and it looks like a limitation of iOS. There are a few suggestions/workarounds here though. This would also explain why it works fine on a different device.

http://css-tricks.com/forums/topic/scrolling-iframe-on-ipad/

Try adding this to the bottom of the multibox.css file and see if this works:

Yes, your solution works like a charm on Ipad; but on desktop now I see double scroll bar (see attached screenshot)

A solution for that might be to add the code with a @mediascreen trigger so it only occurs on smaller resolutions. Wrapping the coding with something like the below and adjusting the 970px to your desired trigger should work.