I have a grid with a large number or columns.The first 4 columns are
frozen. I have some columns that I set the column background color in
the code behind and some i set in the XAML.   For those columns that I
set the background color in the code behind, when i scroll horizontally
and partially obscure it behind the last frozen column, and then I
scroll vertically the color of the the column will show thru the frozen
column.

See Attached picture

Hi,

Generally, we do not recommend working directly with the visual elements in RadGridView as it is a virtualized control and its elements are reused as they are brought in and out the view area. You can check our online documentation explaining how the UI virtualization works. 

May I ask you to share some more details on how do you set the Background of the cells in code behind? What is the result if you disable freezing the columns at all?

Regards,
Dimitrina
Telerik