title: Netbeans GUI Background Color Change on Button Press
body: <p>I'm using Netbeans 6.7.1. I'm making a GUI application. </p>
  
  <p>What I want to have happen when I press a button (btnEnter, I named it) is for the background color of my application to change (not the color of the button, but of the mainPanel). Does anyone know how to achieve this?</p>
  
  <p>Thanks!</p>