How to create style based on default DataGrid style?

Well mystery is solved 🙂

My first code above actually works:

<Style TargetType="{x:Type MyControls:ExtendedDataGrid}" BasedOn="{StaticResource {x:Type DataGrid}}">
    <Setter Property="Template">
    ...
    </Setter>
</Style>

I thought that it is not working becase VS (or Resharper) showed error in my code saying that resource is not found… Bug in VS (or Resharper) 🙁