Scale transforms do not render consistently

Reproduction steps:
Apply a ScaleTransform to the ContentControl in the MainWindow of the demo app.

<ContentControl Content="{Binding ElementName=DemoItemsListBox, Path=SelectedItem.Content}">
    <ContentControl.LayoutTransform>
        <ScaleTransform ScaleX="1.3" ScaleY="1.3" />
    </ContentControl.LayoutTransform>
</ContentControl>

The problem can be observed with most of the controls that have fine lines. ComboBox and TextBox both use the Underline control, and Slider is another obvious one. The issue is that the rendered thickness of these lines is inconsistent.

This problem is typically resolved with the UseLayoutRounding and SnapToDevicePixels

The "fix" for this may be partially or fully in the demo application, in which case those changes should be documented here.

从演示应用的 MainWindow 开始，在 ContentControl 上复现 ScaleTransform，然后比较基于 Underline 的 ComboBox 和 TextBox 控件以及 Slider 中细线的渲染效果。检查 UseLayoutRounding 或 SnapToDevicePixels 是否能解决不一致问题；完成的标准是受影响的控件渲染出一致的线条粗细，并记录对演示应用所做的任何更改。