So I was just playing a game, and as it happened I picked up a box. I actually too a screenshot (killed a guy and hit all three on the player living as well.) And then. I click something that took me out of the gameplay site on armor games!!! I thought I lost my tank coins which I just picked up. When I reloaded the page, there were my tank coins which I had just gotten, added. So now I know, if you close the page, when you get a box with TC's...you still get it. End of my little story.
Unless you get two boxes, then you will only receive one of them after closing the page. So be careful lol.