Bug report: I have tried creating a new Moneybutton wallet with a Powping username for demonstration purposes. In my first attempt at naming the Powping user I used the name bitcoin.demonstration. When I swiped the moneybutton I received the message: "The username is already taken, try a different username". I tried several other usernames all starting with bitcoin.demonstration, but every time I got the same error. Eventually, I tried removing the dot (.) in the username, and then it worked, so the error message Powping displays is not accurate. Powping should tell users which characters are allowed and tell if non-valid characters are entered. Please fix that bug.