title: Which signal can tell me unchecked checkbox?
body: <p>Suppose I have set of <code>QCheckBoxes</code>, I set some of them. I need to understand when I uncheck them, but I don't know which <code>signal</code> can help me?
  The following code tell me checked:</p>
  <pre><code>QtCore.QObject.connect(self.checkBox, QtCore.SIGNAL(_fromUtf8(&quot;isChecked()&quot;)), lambda: self.interfaceCodesConstructor.setFilterDict(self,&quot;name&quot;,self.lineEdit.text()))
  </code></pre>
  <p>and I <code>connect</code> a <code>lambda function</code>.</p>
  <p><strong>My question</strong> is, which <code>signal</code> can  tell me <code>checkbox</code> is unchecked?</p>