title: Create a cocoa button that accepts keyboard input
body: <p>Hey everyone, thanks for all your help so far, I've learned a whole lot in a short amount of time.</p>
  
  <p>What I've done so far is to create a small calculator program and it works nicely.  To complete this version of it, what I'd like to do is make my "keys" on the calculator interface accept input from my keyboard presses.  So, for example, if I want to add 2 and 4, instead of clicking my "2" and "4" buttons, I can just press them on my numeric keypad instead.</p>
  
  <p>I know it has something to do with giving my buttons focus but I can't figure out how to make them respond to keydown events.</p>
  
  <p>I'm looking around on the apple developer documentation as well, so if I find the answers before you guys can then I'll try what I find out, and if it doesn't work I'll post with my progress.</p>
  
  <p>Again, thanks everyone for your help!</p>