title: Qooxdoo : styling individual widgets
body: <p>What is the most convenient way to apply some custom styling to an individual widget element that does not confirm to the default styling of the theme. I am still confused with the usage of decorators . How does one apply multiple decorators eg. for border properties and background to a widget element.</p>
  
  <p>I have tried using custom decorators eg. : </p>
  
  <pre><code>
          var titleBar = new qx.ui.container.Composite();
          titleBar.set({
              decorator : qx.ui.decoration.MBackgroundImage,
                          style : {
                  backgroundImage : '/images/tbar.png'
                          }
          });
  </code></pre>
  
  <p>But I recieve an error : </p>
  
  <p>Error in property decorator of class qx.ui.container.Composite in method setDecorator with incoming value '[Mixin qx.ui.decoration.MBackgroundImage]': Is invalid!</p>