Multiple contents in ControlTemplate

[JumbaJookiba]

I am trying to develop a Custom Control meant to arrange a few views in a certain way (center, left, right, top and bottom).
For this, I created this class:

`
using System.ComponentModel;

namespace MauiApp1
{
[DefaultProperty("Content")]
[ContentProperty("Content")]
public class Grid3x3 : TemplatedView
{
[Bindable(true), Category("Content")]
public IView Top
{
get { return (IView)GetValue(TopProperty); }
set { SetValue(TopProperty, value); }
}

    [Bindable(true), Category("Content")]
    public IView Bottom
    {
        get { return (IView)GetValue(BottomProperty); }
        set { SetValue(BottomProperty, value); }
    }

    [Bindable(true), Category("Content")]
    public IView Left
    {
        get { return (IView)GetValue(LeftProperty); }
        set { SetValue(LeftProperty, value); }
    }

    [Bindable(true), Category("Content")]
    public IView Right
    {
        get { return (IView)GetValue(RightProperty); }
        set { SetValue(RightProperty, value); }
    }
    [Bindable(true), Category("Content")]
    public View Content
    {
        get { return (View)GetValue(ContentProperty); }
        set { SetValue(ContentProperty, value); }
    }

    public static readonly BindableProperty ContentProperty =
        BindableProperty.Create(nameof(Content), typeof(View), typeof(ContentView), null/*, propertyChanged: TemplateUtilities.OnContentChanged*/);

    public static readonly BindableProperty TopProperty =
        BindableProperty.Create(nameof(Top), typeof(IView), typeof(Grid3x3));

    public static readonly BindableProperty BottomProperty =
        BindableProperty.Create(nameof(Bottom), typeof(IView), typeof(Grid3x3));

    public static readonly BindableProperty LeftProperty =
        BindableProperty.Create(nameof(Left), typeof(IView), typeof(Grid3x3));

    public static readonly BindableProperty RightProperty =
        BindableProperty.Create(nameof(Right), typeof(IView), typeof(Grid3x3));
}

}
`

It compiles fine and the app starts, but cannot load this XAML:

`

<ScrollView>
    <ScrollView.Resources>
        <ControlTemplate x:Key="ThreeByThree">
            <Grid Background="{TemplateBinding Background}"
                  BindingContext="{Binding Source={RelativeSource TemplatedParent}}">
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="Auto"/>
                    <ColumnDefinition Width="*"/>
                    <ColumnDefinition Width="Auto"/>
                </Grid.ColumnDefinitions>
                <Grid.RowDefinitions>
                    <RowDefinition Height="Auto"/>
                    <RowDefinition Height="*"/>
                    <RowDefinition Height="Auto"/>
                </Grid.RowDefinitions>
                <ContentPresenter Grid.Column="1" Grid.Row="0" Content="{TemplateBinding BindingContext.Top}"/>
                <ContentPresenter Grid.Column="1" Grid.Row="2" Content="{TemplateBinding BindingContext.Bottom}"/>
                <ContentPresenter Grid.Column="0" Grid.Row="1" Content="{TemplateBinding BindingContext.Left}"/>
                <ContentPresenter Grid.Column="2" Grid.Row="1" Content="{TemplateBinding BindingContext.Right}"/>
                <ContentPresenter Grid.Column="1" Grid.Row="1" Content="{TemplateBinding Content}"/>
            </Grid>
        </ControlTemplate>
    </ScrollView.Resources>
    <VerticalStackLayout
        Spacing="25"
        Padding="30,0"
        VerticalOptions="Center">

        <local:Grid3x3 ControlTemplate="{StaticResource Key=ThreeByThree}">
            <local:Grid3x3.Top>
                <Button Text="Top"/>
            </local:Grid3x3.Top>
            <local:Grid3x3.Bottom>
                <Label Text="Bottom"/>
            </local:Grid3x3.Bottom>
            <local:Grid3x3.Left>
                <StackLayout>
                    <Label Text="1"/>
                    <Label Text="2"/>
                    <Label Text="3"/>
                </StackLayout>
            </local:Grid3x3.Left>
            <local:Grid3x3.Right>
                <Ellipse HeightRequest="60" WidthRequest="60"/>
            </local:Grid3x3.Right>
            <TimePicker/>
        </local:Grid3x3>
    </VerticalStackLayout>
</ScrollView>

`

My problem is that the exception raised has little information: Catastrophic failure (0x8000FFFF (E_UNEXPECTED))
The problem is very similar to the HeaderedControl of WPF, in fact I tried to mimic it with no effect.
If I leave out the four lines positioning the additional contents, everything works fine.

[JumbaJookiba]

I feelso dumb: this solved the problem.

<Border Grid.Column="1" Grid.Row="0" Content="{TemplateBinding Top}"/> <Border Grid.Column="1" Grid.Row="2" Content="{TemplateBinding Bottom}"/> <Border Grid.Column="0" Grid.Row="1" Content="{TemplateBinding Left}"/> <Border Grid.Column="2" Grid.Row="1" Content="{TemplateBinding Right}"/> <ContentPresenter Grid.Column="1" Grid.Row="1" Content="{TemplateBinding Content}"/>