Cannot access parent variable from Iframe in CRM 2016 using turbo form mode

Hi,

How to access parent variable from iframe web resource in crm 2016 using turbo form. When I switched back to Legacy mode I can access the parent variable using code below.

window.parent.myVariable

If I disable legacy form mode and switch back default turbo form mode I cannot access the parent variable. I am getting undefined error.

So the problem is due to turbo form. So is there no way to access the parent variable from iframe using turbo form?