Account groups

It would be very useful for some of us to be able group accounts in any form we want, this is what is keeping me from making the full switch from Money Manager.

One should be able to create an account group and add the accounts you want to that group. Then, in the account summary, the group name would displayed and next to it, the total amount of the accounts in the group summed up, and a chevron to expand or collapse the group.
I think it's somewhat trivial and would be great for a bunch of us and certainly kill all your competition.