title: QFormLayout does not expand widget full height to maximum widget height
body: <p>I have an issue with getting a QTreewidget full height inside a QFormLayout. I'm on Windows 10 and use QT 5.7</p>
  
  <p>Things I tried:</p>
  
  <ul>
  <li>all possible Vertical policy's without success.  Change the</li>
  <li>FieldGrowthPolicy of the layout to AllNonFixedFieldsGrow </li>
  <li>Use another widget, all fail to make this work</li>
  </ul>
  
  <p>That's all the options I found to possibly make this work.</p>
  
  <p>Here's what I try to achieve:
  <a href="https://postimg.org/image/shtvcby0j/" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/NV6O6.png" alt="qtQformLayoutIssue.png"></a>
  </p>
  
  <p>Here's my ui file:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;ui version="4.0"&gt;
   &lt;class&gt;Dialog&lt;/class&gt;
   &lt;widget class="QDialog" name="Dialog"&gt;
    &lt;property name="geometry"&gt;
     &lt;rect&gt;
      &lt;x&gt;0&lt;/x&gt;
      &lt;y&gt;0&lt;/y&gt;
      &lt;width&gt;760&lt;/width&gt;
      &lt;height&gt;747&lt;/height&gt;
     &lt;/rect&gt;
    &lt;/property&gt;
    &lt;property name="windowTitle"&gt;
     &lt;string&gt;Dialog&lt;/string&gt;
    &lt;/property&gt;
    &lt;layout class="QFormLayout" name="formLayout"&gt;
     &lt;item row="0" column="0"&gt;
      &lt;widget class="QLabel" name="label"&gt;
       &lt;property name="text"&gt;
        &lt;string&gt;Please grow the treeview:&lt;/string&gt;
       &lt;/property&gt;
      &lt;/widget&gt;
     &lt;/item&gt;
     &lt;item row="0" column="1"&gt;
      &lt;widget class="QTreeWidget" name="treeWidget"&gt;
       &lt;property name="sizePolicy"&gt;
        &lt;sizepolicy hsizetype="Expanding" vsizetype="MinimumExpanding"&gt;
         &lt;horstretch&gt;0&lt;/horstretch&gt;
         &lt;verstretch&gt;0&lt;/verstretch&gt;
        &lt;/sizepolicy&gt;
       &lt;/property&gt;
       &lt;column&gt;
        &lt;property name="text"&gt;
         &lt;string notr="true"&gt;1&lt;/string&gt;
        &lt;/property&gt;
       &lt;/column&gt;
      &lt;/widget&gt;
     &lt;/item&gt;
    &lt;/layout&gt;
   &lt;/widget&gt;
   &lt;resources/&gt;
   &lt;connections/&gt;
  &lt;/ui&gt;
  </code></pre>