title: thread for callback function in timeout_add
body: <p>On which thread does the callback function gets executed after every "interval" milliseconds when we schedule a function using the following method??</p>
  
  <pre><code>def glib.timeout_add(interval, callback, ...)
  </code></pre>
  
  <p><a href="https://developer.gnome.org/pygobject/stable/glib-functions.html#function-glib--timeout-add" rel="nofollow">https://developer.gnome.org/pygobject/stable/glib-functions.html#function-glib--timeout-add</a></p>