What is the "Login to store" in Admin > Sales > Customer do?

I was playing in the admin site (of 1.5.1.3) and wondered, when I'm looking at a customer's account in Sales > Customers, to the right of the Date Added field is a dropdown with the column name of "Login to Store", and a single value of "Default" in the dropdown. What's it supposed to do?

In my installation it opens up a new, blank window. Is it supposed to do something else?

It logs you into the store as that customer.

I am using 1.5.3.1 and I just see a blank page too.

Has anybody fixed this?