title: WPF datagrid styling errors IDataErrorInfo
body: <p>I'm using MVVM and have a datagrid with an editable column that I'm doing validation on:</p>
  
  <pre><code>&lt;DataGridTemplateColumn Header="Key" Width="80"&gt;
                  &lt;DataGridTemplateColumn.CellTemplate&gt;
                      &lt;DataTemplate&gt;
                          &lt;TextBlock Text="{Binding Key}" /&gt;
                      &lt;/DataTemplate&gt;
                  &lt;/DataGridTemplateColumn.CellTemplate&gt;
                  &lt;DataGridTemplateColumn.CellEditingTemplate&gt;
                      &lt;DataTemplate&gt;
                          &lt;vw:NumericTextBox Text="{Binding Key, Mode=TwoWay,ValidatesOnDataErrors=True,UpdateSourceTrigger=PropertyChanged}"/&gt;
                      &lt;/DataTemplate&gt;
                  &lt;/DataGridTemplateColumn.CellEditingTemplate&gt;
              &lt;/DataGridTemplateColumn&gt;
  </code></pre>
  
  <p>I've put a style in to show the error as a tooltip:</p>
  
  <pre><code>&lt;Style TargetType="{x:Type DataGridCell}"&gt;
      &lt;Style.Triggers&gt;
          &lt;Trigger Property="Validation.HasError" Value="true"&gt;
              &lt;Setter Property="ToolTip" Value="{Binding RelativeSource={x:Static RelativeSource.Self},Path=(Validation.Errors).CurrentItem.ErrorContent}"/&gt;
          &lt;/Trigger&gt;
      &lt;/Style.Triggers&gt;
  &lt;/Style&gt;
  </code></pre>
  
  <p>So the validation is fired and the cell is outlined in red and the error message tooltip is displayed. </p>
  
  <p>I have 2 problems, firstly when the user click out of the cell the cell remains outlined in red but the tooltip isn't displayed when hovered over. How do I get this to work? The second problem is that there is an orange exclamation next to the row which I don't want. I assume this is because of some default styling on the grid or the row. How do I get rid of it (the red outline is fine)?</p>