Hello Tim,
I would suggest to create a custom GroupHeaderContentTemplateSelector as explained
here and add a DataTemplate for the NullGroups:
and in XAML:
<example:CustomGroupHeaderContentTemplateSelector x:Key=
"CustomGroupHeaderContentTemplateSelector"
>
<example:CustomGroupHeaderContentTemplateSelector.HorizontalTemplate>
<DataTemplate>
<Border Background=
"Red"
>
<ContentPresenter Content=
"{Binding FormattedName}"
Height=
"16"
Margin=
"4"
/>
</Border>
</DataTemplate>
</example:CustomGroupHeaderContentTemplateSelector.HorizontalTemplate>
<example:CustomGroupHeaderContentTemplateSelector.VerticalTemplate>
<DataTemplate>
<telerikPrimitives:LayoutTransformControl VerticalAlignment=
"Top"
>
<telerikPrimitives:LayoutTransformControl.LayoutTransform>
<RotateTransform Angle=
"-90"
/>
</telerikPrimitives:LayoutTransformControl.LayoutTransform>
<ContentPresenter Content=
"{Binding FormattedName}"
Margin=
"4"
Height=
"16"
/>
</telerikPrimitives:LayoutTransformControl>
</DataTemplate>
</example:CustomGroupHeaderContentTemplateSelector.VerticalTemplate>
<example:CustomGroupHeaderContentTemplateSelector.NullGroupTemplate>
<DataTemplate>
<Border Background=
"Red"
>
<TextBlock Text=
"Without resource"
Height=
"16"
Margin=
"4"
/>
</Border>
</DataTemplate>
</example:CustomGroupHeaderContentTemplateSelector.NullGroupTemplate>
</example:CustomGroupHeaderContentTemplateSelector>
Hope this helps.
All the best,
Yana
the Telerik team