title: CheckBox does not update
body: <p>I am using a CheckBox as a Toggle Button (checkBox.Appearance = Appearance.Button) in a child form. If the users presses the button a measurement cycle will start if some criteria are satisfied (e.g. temperature within range). The CheckBox.Checked property remains true until the measurement is completed.</p>
  
  <p>If e.g. the temperature is out of range a warning will appear and the button will be reset. The same happens if the cycle ended properly. In the end this self-explaining function is called:</p>
  
  <pre><code>    /// &lt;summary&gt;
      /// Resets the button states to false
      /// &lt;/summary&gt;
      public void ResetButton()
      {
          checkBox_Start.Checked = false;
      }
  </code></pre>
  
  <p>Now, when debugging, I see that the CheckBox_Start.Checked property is false and remains false. BUT the UI does not show the actual value. It seemingly remains checked. I have tried Refresh() and Update() on all levels.</p>
  
  <p>Does anyone have an idea? What could possibly keep the UI from showing the actual value?</p>