title: WPF DataGridCheckBoxColumn check/uncheck sometimes don't work
body: <p>I have a <code>DataGridCheckBox</code> column bound to a field in DB.
  The issue is that sometimes the check/uncheck works right away, and sometimes
  it doesn't, even if I click many times, the click won't stay.
  In these cases, the only thing that solves this is clicking the CheckBox,
  and while <strong>mouse down</strong>, dragging to next field and leave mouse.
  This way the checked/uncheck stays fine...</p>
  
  <p>This is the code:</p>
  
  <pre><code>DataGridCheckBoxColumn x:Name="to_send" Binding="{Binding to_send, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Width="150" Header="האם לשלוח" IsThreeState="False" ElementStyle="{StaticResource {x:Type CheckBox}}"
  </code></pre>
  
  <p></p>
  
  <p>What am I doing wrong ?</p>
  
  <p>I've tried it with DataGridTemplateColumn - Still same problem......</p>
  
  <p>Thanks,
  Ronit.</p>