title: Updating Qlabel Document rectangle called for label that is not a text label. Why?
body: <p>In my code I have the following function that updates a qlabel. The qlabel is updated very frequently. The code is</p>
  
  <pre><code>void foo::someMethod(std:atring a)
  {
       {//begin
       boost::lock_guard&lt;boost::mutex&gt; lock(mutex_label);
       frm-&gt;mylabel-&gt;setText(a.c_str());
       }//end lock
  }
  </code></pre>
  
  <p>And then after a while I get an assertion error:</p>
  
  <pre><code>assert failure in documentRect: "document rect called for label that is not a text label! , file widgets\qlabel.cpp
  </code></pre>
  
  <p>Any suggestions what might be causing it ? Also sometimes the value is never shown. I have to move the form for the values to be updated</p>