MainView

<App Theme="Basic">

<DockPanel>

            <WhileTrue ux:Name="whileTrue">
                <Panel Width="100%" Height="100%" Background="#0000ff">
                    <AddingAnimation>
                        <Move RelativeTo="ParentSize" X="1" Duration="0.25"/>
                        </AddingAnimation>
                    <RemovingAnimation>
                        <Move RelativeTo="ParentSize" X="1" Duration="0.25"/>
                    </RemovingAnimation>
                    <Button Text="Back" Width="100" Height="20" Alignment="TopLeft" ux:Name="button">
                    <Clicked>
                        <Set whileTrue.Value="false"/>
                    </Clicked>
                    <WhilePressed>
                        <Change button.Opacity="0.5"/>
                    </WhilePressed>
                    </Button>
                </Panel>
            </WhileTrue>



<Button Height="40" Width="50%" Text="Show panel">
<Clicked>
    <Set whileTrue.Value="true"/>
</Clicked>
</Button>

</DockPanel>

</App>