title: Why won't the children in my JavaFX HBox grow (SceneBuilder)?
body: <p>The JavaFX <a href="http://docs.oracle.com/javafx/2/api/javafx/scene/layout/HBox.html">docs for HBox</a> say:</p>
  
  <blockquote>
    <p>If an hbox is resized larger than its preferred width, by default it will keep children to their preferred widths, leaving the extra space unused. If an application wishes to have one or more children be allocated that extra space it may optionally set an hgrow constraint on the child. See "Optional Layout Constraints" for details.</p>
  </blockquote>
  
  <p>In the attached image, why isn't the button filling the horizontal width?</p>
  
  <p><img src="https://i.stack.imgur.com/Izbwp.png" alt="enter image description here"></p>
  
  <p>Isn't that the same as the <code>HBox.setHgrow(field, Priority.ALWAYS)</code> code the docs refer to.</p>