title: Why can't set "defaultTextFormat" directly?
body: <p>for example,we can set graphics of a shape directly(without creating an external Graphics variable):  </p>
  
  <pre><code>var my_shape:Shape=new Shape();
  my_shape.graphics.beginFill(0);
  </code></pre>
  
  <p>but that's not same as defaultTextFormat<br>
   the below code doesn't work:</p>
  
  <pre><code>var my_text:TextField=new TextField();
  my_text.defaultTextFormat.size=47;
  </code></pre>
  
  <p>typing dot after defaultTextFormat,the code hint of text format appears and there is no compiler error but still doesn't work<br>
  we must create an external TextFormat variable:</p>
  
  <pre><code>var my_text:TextField=new TextField();
  var my_format:TextFormat=new TextFormat();
  my_format.size=47;
  my_text.defaultTextFormat=my_format;
  </code></pre>
  
  <p>but why can't set directly?
  I don't like a lot of variables.<br>
  after that,explain the difference between textFormat and Graphics.<br>
  Thanks for your help.</p>