title: DataGridCheckBoxColumn updates source and is validated only after focus loss
body: <p>I have a problem with <code>DataGrid</code> from <code>WPFToolkit</code>. My grid has <code>DataGridCheckBoxColumn</code>. When I change value of some cell in this column, validation and real source updating occures only after a cell has lost focus. So, if I change checkbox value in a cell and leave focus inside it, the property of a binded object wouldn't be changed. </p>
  
  <p>Column's binding property <code>UpdateSourceTrigger</code> is set to <code>PropertyChanged</code> and <code>Mode</code> is set to <code>TwoWay</code>. </p>
  
  <p>How can I make binding update my source object immediatly after a checkbox value has been changed?</p>