MList.axaml

<Styles xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:controls="using:Switch_Wallparer.Views.Controls">
    <Design.PreviewWith>
        <controls:MList />
    </Design.PreviewWith>

    <Style Selector="controls|MList">
        <!-- Set Defaults -->
        <Setter Property="Template">
            <ControlTemplate>
                <Grid></Grid>
            </ControlTemplate>
        </Setter>
    </Style>
</Styles>