title: Opacity keeps increasing with each call
body: <p>I'm working on a project where I combined KineticJS with SignalR to update the stage on server calls.</p>
  
  <p>So far everything works pretty good, and for the things that didn't work I had great help with the questions and answers on SO.</p>
  
  <p>However this time I can't get it to work I also can't find any questions with a similar problem.</p>
  
  <p>Basically I'm dynamically generating the init script for the KineticJS stage.(this all works perfectly) the code output looks like this:</p>
  
  <pre><code>var stage = new Kinetic.Stage({
      id: 1,
      container: 'stage-container',
      width: self.baseWidth,
      height: self.baseHeight
  });
  </code></pre>
  
  <p>And for a shape it looks like this:</p>
  
  <pre><code>var shape129 = new Kinetic.Line({
      id: 'shape129',
      points: [249,66, 1889,66, 1889,928, 249,928, 249,66],
      fill: '#DADADA',
      opacity: 1,
      stroke: '#3B5A99',
      strokeWidth: 0,
      closed: true,
      draggable: true
  });
  </code></pre>
  
  <p>So far so good.</p>
  
  <p>It all renders perfectly.</p>
  
  <p>Then the magic happens and I use a SignalR method to change the color of the shape
  With the following code I get perfect color switches but not the desired opacity:</p>
  
  <pre><code>signal.client.statuschange = function (id, message) {
      var shape = Kinetic.stages[0].find('#' + id);
      shape.setAttr('fill', message);
      shape.setOpacity(0.5);
      shape.getLayer().draw();
  };
  </code></pre>
  
  <p>As I said the color changes perfectly but the opacity keeps increasing with each call to the method.</p>
  
  <p>I'm kinda lost here and not sure what is happening and most of all Why it is happening.</p>
  
  <p>Any help would be very much appreciated!</p>