Cannot open CRM Documents when CRM is loaded as a frame inside Zoho Mail

Cannot open CRM Documents when CRM is loaded as a frame inside Zoho Mail

Zoho Mail seems to be the only way of making all the Zoho apps accessible seamlessly in one place.

However CRM is misbehaving if accessed via Zoho Mail. If you try the Documents tab, nothing happens if using Google Chrome. In IE you get the message This content cannot be displayed in a frame. 

Is the Zoho Mail a 'second class' way of using Zoho Apps, should you really use a new tab for each app? Do Zoho plan on making app switching more intuitive?