title: How to perform two-way data binding with a ToggleButton?
body: <p>I have an <code>ObservableBoolean</code> field in my activity class, which is bound to the "checked" attribute of my <code>ToggleButton</code> like so:</p>
  
  <pre><code>android:checked="@{activity.editing}"
  </code></pre>
  
  <p>I was hoping this would create a two-way relationship between the button and the boolean, but it only carries changes from the field to the button, not the other way. What am I doing wrong, or is this not in the scope of Android <code>DataBinding</code>?</p>