Ok, I managed to create the DataGridExt (copy-paste from mx.DataGrid). Don't ask me why I did this, it's a long story believe me.
But it is styleless. There's no skin set and that is what I expected.
The thing is, is there a nice/magical way to tell the DataGrid skin to be applied to DataGridExt?
Thanks for attention.
In case the question was not clear:
Is there a way to have all styles of mx.DataGrid applied to my custom control called DataGridExt?