title: Event handlers in Paper.js
body: <p>I am new to Paper.js, and I was wondered by the event system, while reading tutorial.
  Thats how event hanling described in <a href="http://paperjs.org/tutorials/interaction/mouse-tool-events/" rel="noreferrer">tutorial</a>:</p>
  
  <pre><code>var path;
  function onMouseDown(event) {
      // Create a path:
      path = new Path();
      path.strokeColor = 'black';
      // Add the mouse down position:
      path.add(event.point);
  }
  
  function onMouseUp(event) {
      // Add the mouse up position:
      path.add(event.point);
  }
  </code></pre>
  
  <p>So, its just functions in global namespace...<br>
  Eventually I have a few questions about it, and I didnt found anything on the internet on this:<br>
  - How to bind event handler to particular canvas?<br>
  - How to bind event handler to particular "object" (raster image, rectangle, etc)?<br>
  - How to bind multiple event handlers to something?<br></p>