title: Is there any way to get if react final form has touched status outside of form
body: <p>I use react final form in another component, say dialog div and I want to check was this form changed before close this dialog div (to show a message like 'You have unsaved changes').</p>
  
  <p>Here is an example, I have no idea how to call onChange in a form on final-form changes - in  tag it will not work in case I use some custom input and in validate method it looks too dirty.</p>
  
  <pre><code>class Dialog extends Component {
      ...
      onFormChange = () =&gt; this.setState({isFormChanged: true})
      close() {
          if (this.isFormChanged){
              this.showDialog()
          } else {
              //close dialog
          }
      }
      render(){
          return &lt;div&gt;
              &lt;MyForm onChange={this.onFormChange} /&gt;
          &lt;/div&gt;
      }
  }
  </code></pre>
  
  <p>and a form</p>
  
  <pre><code>function MyForm({ saveData, onChange, ...props }) {
      return &lt;div&gt;
          &lt;Form
              onSubmit={saveData}}
              render={({
                  handleSubmit,
              }) =&gt; (
                  &lt;form onSubmit={handleSubmit} onChange={() =&gt; onChange()}&gt;
                      &lt;/form&gt;
  </code></pre>