Question

How can I access DataGrid area not filled with Cells?

I want to add context menu for this area only

Answer 1

You can assign a ContextMenu to the DataGrid itself for the “Blank” area, but it will also appear for any rows you right-click on, if you don’t have a different context menu assigned to the rows (or the “DataGrid.RowStyle” property).

The ‘workaround’ is to simply assign a different context menu to the rows, specifically.

<DataGrid>
    <DataGrid.ContextMenu>
        <ContextMenu>
            <MenuItem Header="Menu Item in Blank Area" />
        </ContextMenu>
    </DataGrid.ContextMenu>
    <DataGrid.RowStyle>
        <Style TargetType="{x:Type DataGridRow}">
            <Setter Property="ContextMenu">
                <Setter.Value>
                    <ContextMenu>
                        <MenuItem Header="Menu Item just for Populated Rows" />
                    </ContextMenu>
                </Setter.Value>
            </Setter>
        </Style>
    </DataGrid.RowStyle>   
</DataGrid>