How to write style template to Popup control?

I'd recommend wrapping your Popup's Content in something like a ContentControl or a HeaderedContentControl and setting the style of that

<Popup>    <ContentControl Style="{StaticResource PopupContentStyle}">        ...    </ContentControl></Popup>

Example style...

<Style x:Key="PopupContentStyle" TargetType="{x:Type ContentControl}">    <Setter Property="ContentTemplate">        <Setter.Value>            <DataTemplate>                <Grid Width="Auto" Height="Auto" Background="Gray">                   <Grid.RowDefinitions>                        <RowDefinition Height="30"/>                                           <RowDefinition Height="Auto"/>                               </Grid.RowDefinitions>                    <Border BorderThickness="2" CornerRadius="8" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Grid.RowSpan="2">                        <Border.BorderBrush>                            <SolidColorBrush Color="Gray"/>                        </Border.BorderBrush>                        <Border.Background>                            <SolidColorBrush Color="White"/>                        </Border.Background>                    </Border>                    <StackPanel Grid.Row="0">                        <Label Foreground="Blue" Content="Popup_Title"/>                    </StackPanel>                    <GroupBox Grid.Row="1" Header="Popup example content">                        <StackPanel>                                                     <ContentPresenter />                                                 </StackPanel>                   </GroupBox>                      </Grid>            </DataTemplate>        </Setter.Value>    </Setter></Style>

I prefer Rachels an Josh Noes answer, but had some trouble, because IMHO one should define ContentControls property Template in Style rather than ContentTemplate. Set it to a value of ControlTemplate (not DataTemplate) and dont forget its TargetType. Else in my case the solution didn't work. But a real amazing idea, Thank you.

<Style x:Key="PopupContentStyle" TargetType="{x:Type ContentControl}">    <Setter Property="Template">        <Setter.Value>            <ControlTemplate TargetType="ContentControl">                        ...                        <!--Do some templatestuff around Presenter-->                                                     <ContentPresenter />                                                 <!--/Do some templatestuff around Presenter-->                   </GroupBox>                      </Grid>            </ControlTemplate>        </Setter.Value>    </Setter></Style>