diff -r aeb5f203b3eb -r a5111f4e6412 src/document.ui
--- a/src/document.ui	Fri Nov 08 19:05:07 2019 +0200
+++ b/src/document.ui	Fri Dec 13 15:55:56 2019 +0200
@@ -19,12 +19,19 @@
      <property name="orientation">
       <enum>Qt::Horizontal</enum>
      </property>
-     <widget class="QOpenGLWidget" name="viewport"/>
+     <widget class="PartRenderer" name="viewport"/>
      <widget class="QListView" name="listView"/>
     </widget>
    </item>
   </layout>
  </widget>
+ <customwidgets>
+  <customwidget>
+   <class>PartRenderer</class>
+   <extends>QOpenGLWidget</extends>
+   <header>gl/partrenderer.h</header>
+  </customwidget>
+ </customwidgets>
  <resources/>
  <connections/>
 </ui>