child control not hide in double animation canvas height

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WPF

Silverlight

I want develope control like accordian, for that I applies the height animation to canvas when button is click
but I have some controls in that canvas, double animation is working file the canvas height property is redusing and increasing,
but when canvas height property is reduce the child controls are not hide accroding to that canvas height,
so I want to hide that child controls as the canvas height property reducing

here is my xaml code,

<Window x:Class="WpfApplication2.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="600" Width="525">
  
    
    <Canvas Width="500" Height="450">
        <StackPanel Width="500" Height="450">
            <Button Width="500" Height="25" Click="Button_Click_1"></Button>
            <Canvas x:Name="cnvOrng" Width="500"  Background="Orange">
                <StackPanel>
                    <StackPanel>
                        <Button Style="{StaticResource type-btn}">
                            <StackPanel Orientation="Horizontal" Style="{StaticResource type-button-sp}">
                                <Image Source="Images/check.png" Style="{StaticResource check-image}"></Image>
                                <TextBlock Style="{StaticResource type-Text}">01</TextBlock>
                            </StackPanel>
                        </Button>
                        <Button Style="{StaticResource type-btn}">
                            <StackPanel Orientation="Horizontal" Style="{StaticResource type-button-sp}">
                                <Image Source="Images/check.png" Style="{StaticResource check-image}"></Image>
                                <TextBlock Style="{StaticResource type-Text}">02</TextBlock>
                            </StackPanel>
                        </Button>
                        <Button Style="{StaticResource type-btn}">
                            <StackPanel Orientation="Horizontal" Style="{StaticResource type-button-sp}">
                                <Image Source="Images/check.png" Style="{StaticResource check-image}"></Image>
                                <TextBlock Style="{StaticResource type-Text}">03</TextBlock>
                            </StackPanel>
                        </Button>
                      
                    </StackPanel>
                </StackPanel>

            </Canvas>
          
        </StackPanel>
    </Canvas>
</Window>

Thanks.