Disable inputting of decimal numbers. PMT #98239

@sdreher I added this code because I thought it was annoying that, when I entered a digit in an input, it would always be prepended by a 0. This code "corrects" the user's input, so it might be non-intuitive. I'm not sure if this an improvement or not.. it's just an idea. Let me know if you think I should remove it.