title: add a ToolTip on a DataGridTextColumn
body: <p>I have a DataGrid with some DataGridTextColumn like this:</p>
  
  <pre><code>&lt;DataGrid x:Name="DonneesBrutes" IsReadOnly="True" ItemsSource="{Binding Path=ResultatCollectionGrande}" Margin="10,65,0,0" AutoGenerateColumns="False" EnableRowVirtualization="True" RowDetailsVisibilityMode="VisibleWhenSelected"&gt;
      &lt;DataGrid.Columns&gt;
          &lt;DataGridTextColumn x:Name="PrisEnCompte" Binding="{Binding Path=Flag}" Header="Pris En Compte"&gt;&lt;/DataGridTextColumn&gt;
          &lt;DataGridTextColumn x:Name="PMRQ" Width="*" Binding="{Binding Path=Pmid}" Header="PMID"&gt;&lt;/DataGridTextColumn&gt;
          &lt;DataGridTextColumn x:Name="Ligne" Width="40" Binding="{Binding Path=Ligne}" Header="Ligne" IsReadOnly="True"&gt;&lt;/DataGridTextColumn&gt;
          &lt;DataGridTextColumn x:Name="LibellePMRQ" Width="*" Binding="{Binding Path=LibellePmrq}" Header="Libellé PMRQ"&gt;
              &lt;DataGridTextColumn.HeaderStyle&gt;
                  &lt;Style TargetType="DataGridColumnHeader"&gt;
                      &lt;Setter Property="ToolTip"
          Value="{Binding RelativeSource={RelativeSource Self},
                          Path=Column.(ToolTipService.ToolTip)}"/&gt;
                  &lt;/Style&gt;
              &lt;/DataGridTextColumn.HeaderStyle&gt;
          &lt;/DataGridTextColumn&gt;
          &lt;DataGridTextColumn x:Name="OTM" Width="*" Binding="{Binding Path=Otm}" Header="OTM"&gt;&lt;/DataGridTextColumn&gt;
          &lt;DataGridTextColumn x:Name="TOTM" Width="50" Binding="{Binding Path=Totm}" Header="TOTM"&gt;&lt;/DataGridTextColumn&gt;
          &lt;DataGridTextColumn x:Name="LibelleTOTM" Width="*" Binding="{Binding Path=LibelleTotm}" Header="Libellé TOTM"&gt;
              &lt;DataGridTextColumn.HeaderStyle&gt;
                  &lt;Style TargetType="DataGridColumnHeader"&gt;
                      &lt;Setter Property="ToolTip"
          Value="{Binding RelativeSource={RelativeSource Self},
                          Path=Column.(ToolTipService.ToolTip)}"/&gt;
                  &lt;/Style&gt;
              &lt;/DataGridTextColumn.HeaderStyle&gt;
          &lt;/DataGridTextColumn&gt;
          &lt;DataGridTextColumn x:Name="GA" Width="70" Binding="{Binding Path=GroupeAlerte}" Header="GA"&gt;&lt;/DataGridTextColumn&gt;
          &lt;DataGridTextColumn x:Name="Discipline" Width="120" Binding="{Binding Path=Discipline}" Header="Discipline"&gt;&lt;/DataGridTextColumn&gt;
          &lt;DataGridTextColumn x:Name="DisciplineSubstituee" Width="120" Binding="{Binding Path=DisciplineSubstituee}" Header="Discipline Substituée"&gt;&lt;/DataGridTextColumn&gt;
          &lt;DataGridTextColumn x:Name="Remarque" Width="*" Binding="{Binding Path=.Remarque}" Header="Remarque"&gt;&lt;/DataGridTextColumn&gt;
  
      &lt;/DataGrid.Columns&gt;
  &lt;/DataGrid&gt;
  </code></pre>
  
  <p>I want to create a popup when the mouse over my DataGridTextColumn <code>LibelleTOTM</code>. To perform this, I have done:</p>
  
  <pre><code>&lt;DataGridTextColumn x:Name="LibelleTOTM" Width="*" Binding="{Binding Path=LibelleTotm}" Header="Libellé TOTM"&gt;
      &lt;DataGridTextColumn.HeaderStyle&gt;
          &lt;Style TargetType="DataGridColumnHeader"&gt;
              &lt;Setter Property="ToolTip"
                      Value="{Binding RelativeSource={RelativeSource Self},Path=Column.(ToolTipService.ToolTip)}"/&gt;
          &lt;/Style&gt;
      &lt;/DataGridTextColumn.HeaderStyle&gt;
  &lt;/DataGridTextColumn&gt;
  </code></pre>
  
  <p>I have found this solution on internet but it doesn't works on my solution. I have adapted this to my case, but probably not enough... when the mouse is over the LibelleTOTM, nothing happens. Is the <code>TargetType</code> wrong, can't I bind itself like this? I want to open a popup with the value of the DataGridTextColumn, so sending in <code>ToolTip</code> the <code>Binding="{Binding Path=LibelleTotm}"</code> we find on the <code>&lt;DataGridTextColumn x:Name="LibelleTOTM" Width="*" Binding="{Binding Path=LibelleTotm}" Header="Libellé TOTM"&gt;</code></p>
  
  <p>If anyone has an idea about what missing there, what's wrong and what should I do to perform this?</p>
  
  <p>Thanks in advance.</p>
  
  <p>Flo.</p>