A consumer has confirmed that Steam Wallet is compatible for in-game purchases.
Visit this topic on the forum if you have any further questions.
By default, to increase your game screen size, press the plus sign on your keyboard. Conversely, if you want to decrease your game screen size, then press the minus sign.
To learn more about game controls, visit this wiki article.
I think it is a mere coincidence in your case. Either so, or this is the first I've heard of such a glitch. If this continues, I suggest you read this article.
Customer support service by UserEcho