Seems like just barely cracking your window to slide out the license would raise a huge amount of suspicion to the officer. He would then ask you to exit the vehicle and try to probe around.
Seems like a better way is just to not talk that much and have all of your documentation handy before he walks up so he doesn't have to stick around your window too long. Also, when the officer asks you "do you know why I pulled you over", always say "I don't know" - he is just collecting evidence.
Seems like just barely cracking your window to slide out the license would raise a huge amount of suspicion to the officer.
An officer can have all the suspicion he wants, but without evidence, he can do nothing legally.
If he steps beyond his legal authorization, everything beyond that point in time, will not be allowed as evidence in a court of law.