This link does not open in a new window when you click it. Why is this a problem? Because if you are just trying to double check a design dimension after having uploaded or typed out your details, you will lose everything. This can be solved with a single line of code.
Dimensions should (and could easily be) displayed next to or on top of the product upload boxes. It's sort of silly that they are not as this is the standard across the web for any sort of upload that requires specific dimensions.
I suggest Implementing both changes. Thank you for listening.