I have a gridview with two grouping columns. I want to add some images to the group column header
<t:RadGridView x:Name="WorksGridView" Grid.Column="1"
AutoGenerateColumns="False"
ShowGroupPanel="False"
IsFilteringAllowed="False"
CanUserSortColumns="False"
IsReadOnly="True"
SelectionMode="Single"
SelectionUnit="FullRow"
RowIndicatorVisibility="Visible"
IsSynchronizedWithCurrentItem="True"
RowLoaded="RadGridView_RowLoaded"
GroupRenderMode="Flat"
ItemsSource="{Binding WorksGridBinding, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
SelectedItem="{Binding WokrSelectedItem, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
CurrentItem="{Binding WorkCurrentItem, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" >
<t:RadGridView.GroupDescriptors>
<t:GroupDescriptor Member="Groups" SortDirection="Ascending" />
<t:GroupDescriptor Member="Subgroups" SortDirection="Ascending" >
<t:GroupDescriptor.AggregateFunctions>
<t:CountFunction Caption="Entries count: " />
</t:GroupDescriptor.AggregateFunctions>
</t:GroupDescriptor>
</t:RadGridView.GroupDescriptors>
<t:RadGridView.Columns>
<t:GridViewDataColumn Width="*" HeaderTextAlignment="Center" Header="Works" HeaderCellStyle="{StaticResource HeaderStyle}">
<t:GridViewDataColumn.CellTemplate>
<DataTemplate>
<DataGridCell>
<TextBlock Text="{Binding Title}" FontSize="14" HorizontalAlignment="Left" />
</DataGridCell>
</DataTemplate>
</t:GridViewDataColumn.CellTemplate>
</t:GridViewDataColumn>
</t:RadGridView.Columns>
</t:RadGridView>