Add a property to the RadGridView that provides a distinct template for adding a new row.
Sometimes you have classes with no default constructor. Those classes may have properties that are read-only after construction. This cannot be handled in the RadGridView, because you only have the choice of a CellEditTemplate. (I'm envisioning something akin to the RowDetailsTemplate.)
Example: I have a class that defines a invoice match for payment application. Once the invoice is set it cannot be changed. The user can still edit the match, but they're only allowed to edit the amount to be applied.
The content of the cell is set from .LoadContent() method and is returned from the CreateCellElement method of the column.
One possible scenario for a fix is to change that behavior and apply directly the template as WPF DataGrid does. However, this is a huge breaking change with CreateCellElement method is widely used. The second approach is to leave the code as it is right now, return the element from method of DataTemplate and set the ContentTemplate property of the cell to that DataTemplate. This will cause the content to be loaded twice. Which will degrade theWhen the ItemsSource of the RadGridView is reset, disctinct values remain checked in the Filtering Popup.
For a workaround, check the attached project.
Group rows which are not present in the view are not visualized when the window is maximized.
A possible solution here is to set the GroupRenderMode property to Flat.