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.
