How do you bind a ContentTemplate directly to a Grid?

Question

In the following XAML, I am trying to bind the various DataTemplates directly to the Grid ContentPresenter. I have put the Button inside the Grid just to prove to myself that the ContentTemplate is binding and the DataTriggers are working correctly - which they are (note I don't want any type of control at this point). If I replace <Button> with <ContentPresenter> nothing shows up. Obviously I'm missing something really simple here.

      <DataTemplate x:Key="MyTemplate">
        <Grid Style="{StaticResource GridAllocatedStyle}">
            <Ellipse Stroke="#FF5A71FB" 
                     StrokeThickness="0.5"
                     Style="{StaticResource EllipseFinanciallyAllocatedStyle}" />
            <TextBlock Style="{StaticResource TextBlockInsideEllipseStyle}" 
                       Text="A"
                       ToolTip="Allocated" />
        </Grid>
    </DataTemplate>


    <DataTemplate x:Key="AllocationTemplate">
        <Grid>           
            <Button> <!-- I want to bind to the Grid.ContentPresenter here -->
                <Button.Style>
                    <Style TargetType="Button">                             
                        <Style.Triggers>                               
                            <DataTrigger Binding="{Binding Allocated}" Value="PreAllocatedBoth">
                                <Setter Property="ContentTemplate" Value="{StaticResource MyTemplate}" />
                            </DataTrigger>
                        </Style.Triggers>
                    </Style>
                </Button.Style>
            </Button>            
        </Grid>      
    </DataTemplate>

For completeness this is what I'm trying to achieve:

 <DataTemplate x:Key="AllocationTemplate">
        <Grid>
            <Grid.Style>
                <Style TargetType="Grid">                    
                    <Style.Triggers>
                        <DataTrigger Binding="{Binding Allocated}" Value="None">
                            <Setter Property="Visibility" Value="Collapsed" />
                        </DataTrigger>                       
                    </Style.Triggers>
                </Style>
            </Grid.Style>
            <ContentPresenter> <!-- I want to bind to the Grid.ContentPresenter here -->
                <ContentPresenter.Style>
                    <Style TargetType="ContentPresenter">                             
                        <Style.Triggers>
                            <DataTrigger Binding="{Binding Allocated}" Value="FinanciallyAllocated">
                                <Setter Property="ContentTemplate"  Value="{StaticResource MyTemplate}" />
                            </DataTrigger>                                                          
                        </Style.Triggers>
                    </Style>
                </ContentPresenter.Style>
            </ContentPresenter>            
        </Grid>      
    </DataTemplate>

Answer 1

Maybe nothing shows up because you do not have any content set in your contentPresenter?

p.s.: it looks like you have a lot of code which doesn't relate to the your issue (ellipse styles, many templates). It takes a while to go through all this code, so I'd ask to remove unneeded code.