title: how can I control mobx observer?
body: <p>I had a problem when I used observer function in <code>react-mobx</code>.<br>
  My source code like following,  </p>
  
  <pre><code>import React from 'react';
  import { observer } from 'mobx-react';
  
  @observer
  class Test extends React.Component{
    render(){
      const { student } = this.props; // it's @observable object
  
      return (
        &lt;div&gt;{student.name}&lt;/div&gt;
      )
    }
  }
  </code></pre>
  
  <p>This component will rerender when <code>student</code> object is changed.<br>
  but I want to control when to re-render.</p>
  
  <p>In short, I want to catch the point when this component re-render.<br>
  (It means <code>student</code> component was changed)<br>
  It's similar shouldComponentUpdate.<br>
  so I thought I can control using shouldComponentUpdate. but it doesn't work.</p>
  
  <p>so how can I control this?<br>
  The final result I want is I don't want to re-render when the <code>student</code> component has certain parameter when it's re-render.</p>