The UI is not updated when an item is replaced in the bound ListCollectionView. 

Workaround: Remove the item and add a new one.

Reset by Clear, RemoveRange causes a memory leak of GridViewRow instances (or TreeListViewRow in RadTreeListView).
To work this around, you can call the Clear method of the RadGridView's Items collection and then reset the ItemsSource property.

this.radGridView.Items.Clear();
this.radGridView.ItemsSource = null;
this.radGridView.ItemsSource = newSource;
Edit: The number of instances of the GridViewRow class are relative to the number of containers which cover the visible viewport. They are kep by internal caching mechanism used for faster reuse of containers is data-reload scenarios. Containers are dettached from their previous viewmodels (DataContext).

In non virtualized scenario, the number of the live containers is the same as the number of items in the GridView's ItemsSource and when changing the source, the number remains the same as the items in the source.

We are closing this issue as we think the mentioned internal cache shouldn't be considered a memory problem but rather a powerful performance optimization internal tool for extensive data-refresh scenarios.

Hi,

I am currently having issues with RadGridView's group footer: I am trying to add a button to the footer template which is supposed to trigger a command which in turn needs some info on the group it was triggered from*.

Since (unlike the header) there does not seem to be any info on the group available directly within the GroupFooterTemplate, I am pulling the group info from the parent GridViewGroupFooterRow:

                <telerik:GridViewDataColumn [...]>
                    <telerik:GridViewColumn.GroupFooterTemplate>
                        <DataTemplate>
                            <Button Command="{Binding DataContext.ShowFooterGroupCommand, RelativeSource={RelativeSource AncestorType=telerik:RadGridView}}"
                                    CommandParameter="{Binding Group.Key, RelativeSource={RelativeSource AncestorType=telerik:GridViewGroupFooterRow}}" />
                        </DataTemplate>
                    </telerik:GridViewColumn.GroupFooterTemplate>
                </telerik:GridViewDataColumn>

This is working great as long as the RadGridView does not use Row virtualization. However, when I turn on Row virtualization and scroll around for a bit, the value I get passed as the CommandParameter is more or less random and has nothing to do with the group my button is actually located in.

I attached a small example project (.Net 6 but our app uses 4.8 so I set that as the Framework below) for you to try it yourself. Just scroll around and click the buttons while watching the debug output window. You will see that the groups in the output window will not match the group where you actually clicked the button after some scrolling.

Expected Behavior

Even when virtualizing, the Group key returned when binding to GridViewGroupFooterRow.Group(.Key) should reliably return the key of the actual group my button is placed in. It would be even better if it was somehow possible to get the group directly, without having to resort to FindAncestor.

Regards
Simon Müller
Hofmann Fördertechnik GmbH

* Basically I am trying to give the user a possibility to add new items to the individual groups and I don't want to add the button to the group header since that makes it too easy to accidentally hit the header's RadToggleButton, collapsing the group.

 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.

The content of the cell is set from .LoadContent() method and is returned from the CreateCellElement method of the column. 

The vertical scrollbar measure incorrectly when the control's ItemsSource is populated in its Loaded event. To reproduce this, set the ItemsSource when the control is initialized. And then populate it on Loaded. Also, to reproduce this you will need to define the columns manually.

To resolve this, populate the data on initialization of the gridview. Or delay the population to happen after the Loaded event. You can use a dispatcher for this.

For the time being, an appropriate converter should be used for the bindings.