In order to same the header text for the first 3 columns, I use the event "PrepareCell" event in the StringNameColumn. The StringNameColumn is used for the first 3 columns.
My solution works (Expando.png+SringNameColumn.PrepareCell), but I'm sure there is a better way, because with my solution the header text will be set over and over for each row!
Is there a better way? In this documentation page, I saw: https://docs.telerik.com/devtools/universal-windows-platform/controls/raddatagrid/columns/datagrid-overview?msclkid=9d05cf25c64c11ecac794eb0f892e42a
- Mixed - by adding columns to the RadDataGrid.Columns collection and also set RadDataGrid.AutoGenerateColumns="True"
but I didn't find any documentation on how to achieve this. Do you have an example of mixed mode?