title: Gtk::Label update label speed
body: <p>I have a program that tries to update a Gtk::Label at a very high frequency, and is exhibing very unstable behaviour. I get several of these errors:</p>
  
  <pre><code>(gtkWindow:26559): Pango-CRITICAL **: pango_layout_copy: assertion 'PANGO_IS_LAYOUT (src)' failed
  
  (gtkWindow:26559): Pango-CRITICAL **: pango_layout_set_width: assertion 'layout != NULL' failed
  
  (gtkWindow:26559): Pango-CRITICAL **: pango_layout_get_pixel_extents: assertion 'PANGO_IS_LAYOUT (layout)' failed
  
  (gtkWindow:26559): GLib-GObject-CRITICAL **: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
  </code></pre>
  
  <p>until the program eventually crashes with:</p>
  
  <pre><code>Pango:ERROR:pango-layout.c:3916:pango_layout_check_lines: assertion failed: (!layout-&gt;log_attrs)
  </code></pre>
  
  <p>2921
      Aborted (core dumped)</p>
  
  <p>The relevant code lines: </p>
  
  <pre><code>while(1){
      std::string sensorLine="";
      _serial.readLine(&amp;sensorLine);         // read serial data with boost::asio
      _output-&gt;set_label(sensorLine.data()); // _output -&gt; Gtk::Label*
      std::cout&lt;&lt;sensorLine&lt;&lt;std::endl;
      //sleep(1);
  }
  </code></pre>
  
  <p>I only get the error if I try to use <code>_output-&gt;setlabel</code>, if I comment this line everything  runs smoothly, with the output printed in the console. The same thing happens if I call <code>sleep()</code>inside the loop, the <code>Gtk::Label</code> is updated as the commandline and no errors are thrown. 
  This loop is running on a separate thread that receives _output as argument.</p>