The goal of this tutorial is to show you how to change the Background for a disabled Cell/Row.
When the GridView is not enabled (i.e. its property IsEnabled is set to False), then you cannot change the Background of its rows/cells.
Please note that once you disable RadGridView, GridViewRow, GridViewColumn, GridViewCell you perform this logic on a cell level. For example when you disable the whole grid, a gray border appeared and you cannot change the Background, MouseOver and Selection effects are lost also.
If you want to maintain these effects you should predefine the template of GridViewCell and modify the Border element named Background_Disabled. You should change its background color to a color, which allows transparency.