title: Opera doesn't trigger mouseup on right mouse button release, workaround?
body: <p>I'm trying to write a collaborative whiteboard drawing application. When the user uses the left (main) mouse button, they should be able to draw in black, and when they use the right mouse button, they should be able to draw in white (eraser). </p>
  
  <p>To keep track of whether the mouse is down, I'm using the following code:</p>
  
  <pre><code>var mouseIsDown = false;
  canvas.addEventListener('mousedown', function(event){
    mouseIsDown = true;
    console.log('mousedown');
  }, false);
  
  canvas.addEventListener('mouseup', function(event){
    mouseIsDown = false;
    console.log('mouseup');
  }, false);
  </code></pre>
  
  <p><strong>Based on my testing, Opera does not trigger the <code>mouseup</code> event when the right mouse button is released.</strong></p>
  
  <p>Is there any workaround from which I can achieve the functionality I need, in detecting whether or not the right mouse button is down?</p>