How to set the width of TimePicker?

[suoyukii]

I want to make the width of the TimePicker the same as the width of the parent control, but no matter how I set the width, it doesn't work.

[seishinkouki]

Name your TimePicker Classes like InfinityWidth

<Style Selector="TimePicker.InfinityWidth">
    <Setter Property="HorizontalAlignment" Value="Stretch"/>
    <Style Selector="^ /template/ Button#PART_FlyoutButton">
        <Setter Property="MaxWidth" Value="Infinity"/>
    </Style>
</Style>

[robloo]

Note that the Date/TimePickers do NOT allow changing size very well. This is unfortunatley due to their lineage from UWP rather than WPF. See #17515 (comment)