title: Qt Creator won't allow me to run GUI Application
body: <p>I am currently using Qt Creator on Ubuntu Linux 12.10, and I have just started a Qt GUI application. When I click the design tab, I come to this screen:</p>
  
  <p><img src="https://i.stack.imgur.com/IZcoQ.png" alt="enter image description here"></p>
  
  <p>As you can see, the Build and Run buttons on the bottom left are greyed out, and I don't understand why. I have searched across the web already, and have found nothing. Can anybody give me a clue as to why this is happening? Have I done something wrong?</p>
  
  <p>My QT Creator version is: </p>
  
  <blockquote>
    <p>Qt Creator 2.5.2<br>
    Based on Qt 4.8.2 (64 bit)<br>
    Built on Aug 19 2012 at 15:28:17</p>
  </blockquote>
  
  <p>The only reason that I switched to Qt Creator is that Qt Designer cannot build applications, or edit their source code. Are the two meant to be used together? If so, how?</p>