title: Check if class extends another class
body: <p>To be clear, I want to check a class, not an instance of that class.</p>
  
  <pre><code>public function changeScene(newScene:Class):void 
  {
    if(newScene isExtending Scene)
    //...
  }
  </code></pre>
  
  <p>It's a variable of type Class.</p>
  
  <p>Edit: More details.
  What the function does (simplified):</p>
  
  <pre><code>public function changeScene(newScene:Class):void 
  {
      currentScene.finish(); //Finish the scene that is about to change
  
      //Check if the new scene don't exist prior this point
      if (!scenes[newScene])  //Look in dictionary
          addScene(newScene); //Create if first time accessing it
  
      scenes[newScene].caller = currentScene["constructor"];
      currentScene = scenes[newScene];
      currentScene.start();
  }
  </code></pre>
  
  <p><a href="https://stackoverflow.com/questions/28205385/when-using-the-class-datatype-how-can-i-specify-the-type-so-i-only-accept-sub/28220451#28220451">This question</a> doesn't work for me because I don't create new instances all the time, I reused them most of the time. The instances are stored in a dictionary using the class as the key.</p>