title: VB.NET - How to make textbox accept only one character per keypress?
body: <p>My project is to simulate the Enigma Machine and I need some help dealing with the visual interface.</p>
  
  <p>In my program I need to have a textbox in which the user can enter an unlimited number of letters. However, the program also updates other components based on the text entered, and displays a visual representation for the user.</p>
  
  <p>For example, when I press the letter 'A' the program encodes it to say, the letter 'S' and displays an image into the interface. However, that encoding is unique every time the letter is encoded.</p>
  
  <p>As you know, when you keep a letter pressed on the keyboard for a longer time, it keeps writing that letter. For example, if I keep 'A' pressed, in my textbox I end up with 'AAAAAAAAAAAAAAAAAAAAAA', and it spams the image display as it encodes every single 'A'.</p>
  
  <p>My question is: How can I limit the textbox to accept only one letter per keypress, but still allowing double or triple letter? So I can have a substring of identical characters, as long as I input them by pressing repeatedly on the keyboard.</p>
  
  <p>I need this so the encoded leter lights up for as long as the input letter is being pressed.</p>