Want WPF DataGrid tooltip to behave like Excel Cell Comments

Question

This is the behaviour i get from an Excel Cell that has comments:

1) Put mouse anywhere on the cell and the comment pops-up like a yellow tooltip;

2) Comment will stay up indefinitely for as long as mouse cursor remains on the cell

I need similar functionality on the DataGridColumnHeader only.

I started off as follows:

   <DataGridTextColumn Binding="{Binding Path=SomeProperty}">
      <DataGridTextColumn.Header>
         <TextBlock Text="MyColHeader" Background="red" >
           <TextBlock.ToolTip>
              <StackPanel Width="400">
                within stack panel make format as fancy as i like, works great;
              </StackPanel>    
           </TextBlock.ToolTip>
        </TextBlock>
      </DataGridTextColumn.Header>
   </DataGridTextColumn>

Problem with that is tooltip only pops-up when mouse hovers on the text of the column header, i.e. in my example on the text "MyColHeader" and NOT anywhere on the cell.

After another hour i came up with something that address point 1):

<DataGridTextColumn
  Header="MyColHeader"
  Binding="{Binding Path=SomeProperty}">
   <DataGridTextColumn.HeaderStyle>
     <Style TargetType="{x:Type DataGridColumnHeader}">
      <Style.Triggers>
         <Trigger Property="IsMouseOver" Value="True">
         <Setter Property="ToolTip">
            <Setter.Value>
               <StackPanel Width="400">
                 make formatting as fancy as i like, works great;
              </StackPanel>
             </Setter.Value>
            </Setter>
           </Trigger>
         </Style.Triggers>
    </Style>
    </DataGridTextColumn.HeaderStyle>
</DataGridTextColumn>

Much better now, remaining question is i need to address point 2), i.e. Make the tooltip stay on indefinitely as long as cursor is over the col header.

Answer 1

You need to set ToolTipService.StaysOpen on the TextColumn as described here: Forcing a WPF tooltip to stay on the screen