title: Where is Qt QOpenGLWidget?
body: <p>I'm trying to write a C++ application that uses QOpenGLWidget, but Qt Creator gives a &quot;'QOpenGLWidget' file not found&quot; error on this line:</p>
  <pre><code>#include &lt;QOpenGLWidget&gt;
  </code></pre>
  <p>The documentation says QOpenGLWidget was introduced in Qt 5.4, and I believe I am running Qt 5.12.1; <code>qmake --version</code> gives:</p>
  <pre><code>QMake version 3.1
  Using Qt version 5.12.1 in /home/oreilly/Qt5.12.1/5.12.1/gcc_64/lib
  </code></pre>
  <p>Moreover, in the Qt Creator menu Tools -&gt; Options... -&gt; Kits also indicates Qt 5.12.1. And Qt Creator allows me to use <code>#include &lt;QOpenGLWindow&gt;</code> (also introduced in Qt 5.4 along with QOpenGLWidget), compile and link the OpenGL application without error.</p>
  <p>What am I doing wrong? Where is QOpenGLWidget?</p>