Maybe I did not express myself clearly. I was suggesting disabling 'enter' and 'space' keys in the popup window, not blocking the ability to create manual rules..
Blocking the network traffic after the harm was done is not a solution.
I am using eset Smart Security/Internet Security with interactive firewall for at least 7 years. From my experience as a user, I can assure this is a real problem with the product, and this is happening at least once per week.
Just imagine a popup from an attacker incoming connection is allowed by mistake right when you are about to press enter or space for various reasons.