We have a working filter column that extends GridTemplateColumn.
Everything is working properly at runtime, but at design time we get this message:
Warning 1:
Generation of designer file failed: Telerik.Web.UI.GridColumnCollection must have items of type 'Telerik.Web.UI.GridColumn'. 'custom:FilteringColumn' is of type 'TIPWebCommon.FilteringTemplateColumns.FilteringColumn'.
We are using Visual Studio 2008 with SQL Server 2005.