I posted this question in an other board and nobody answered so I am reposting this here since Telerik admins are more active in this place.
In this picture
you can see that the "Country" column has been highlighted and is
active (i.e. has Distinct Filter). But in this case, that little
wine-glass-like icon on the left is grey instead of orange. Do you know
how I can make that icon change colour when the column is active?
The classes that are involved are RadGridView, a class that overrides IFilteringControl, and a set of GridViewColumns.