Should be a check box to use free credits (building and specs.)

Instead of being forced to use the credits you gain from an attack immediately (or from war wins...) maybe I want to wait until my economy is trashed to use my credits. Certainly makes winning a war even more valuable, so this may have to be balanced with he bonus given from a war win?

Just a thought I have had for ages and never posted. I imagine some people will be able to come up with some ways to abuse this?