title: What is qobject_cast?
body: <p>Could someone explain in as simple terms as possible (or as simple as you would like) what <code>qobject_cast</code> is, what it does and why we would need to cast one class type to another?</p>
  
  <p>Like, I get typecasting in the sense of casting an <code>int</code> as a <code>char</code> or <code>QString</code> maybe to use <code>QMessageBox</code>, but why cast into different classes?</p>