<Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="auto" />
            <RowDefinition />
        </Grid.RowDefinitions>
        <ToggleButton
            Grid.Row="0"
            Width="40"
            Height="22"
            Margin="10,10,0,10"
            HorizontalAlignment
 
="Left">
            <ToggleButton.Triggers>
                <EventTrigger RoutedEvent="ToggleButton.Checked">
                    <BeginStoryboard>
                        <Storyboard Storyboard.TargetName="bule" Storyboard.TargetProperty="Width">
                            <
 
DoubleAnimation
                                BeginTime="0:0:0"
                                From="0"
                                To="100"
                                Duration="0:0:0.5" />
                        </Storyboard>
                    </BeginStoryboard>
                </
 
EventTrigger>
                <EventTrigger RoutedEvent="ToggleButton.Unchecked">
                    <BeginStoryboard>
                        <Storyboard Storyboard.TargetName="bule" Storyboard.TargetProperty="Width">
                            <DoubleAnimation
                                BeginTime="0:0:0"
                                From="100"
                                To="0"
                                Duration="0:0:0.5" />
                        </Storyboard>
                    </BeginStoryboard>
                </EventTrigger>
            </ToggleButton.Triggers>
        </ToggleButton>
        <Grid Grid.Row="1">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="auto" />
                <ColumnDefinition />
            </Grid.ColumnDefinitions>
            <StackPanel
                x:Name="bule"
                Grid.Column="0"
                Height="{Binding ElementName=stackPanel, Path=ActualHeight}"
                Background="Blue" />
            <StackPanel
                Grid.Column="1"
                Height="{Binding ActualHeight, ElementName=stackPanel}"
                Background="Red" />
        </Grid>

    </Grid>