WPF globally styling a TextBlock inside a DataGrid

So with a bit more digging and a little luck, I discovered that WPF does not apply implicit styles inside templates unless the TargetType derives from Control. Since TextBlock doesn't derive from Control, its style is not applied. So you either have to manually apply the style to every non-Control or define the implicit style inside the template.

The following MSDN blog post explains it in pretty good detail.

https://docs.microsoft.com/en-us/archive/blogs/wpfsdk/implicit-styles-templates-controls-and-frameworkelements

Unfortunately, like BrianP said, WPF does not work that way. But, it is possible to set the TextElement properties of the cell style as follows:

<DataGrid ItemsSource="{Binding Data}" AutoGenerateColumns="False" DockPanel.Dock="Top">
    <DataGrid.CellStyle>
        <Style TargetType="DataGridCell">
            <Setter Property="TextElement.Foreground" Value="Green" />
        </Style>
    </DataGrid.CellStyle>
    <DataGrid.Columns>
        <DataGridTemplateColumn Header="Test">
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <TextBlock Text="not globably applied" />
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>
    </DataGrid.Columns>
</DataGrid>