UIElement.RasterizationScale does not change when Display Scale changes; XamlRoot.RasterizationScale does.

[karmeye]

Describe the bug

XamlRoot.RasterizationScale and UIElement.RasterizationScale have the same documentation:

Gets a value that represents the number of raw (physical) pixels for each view pixel.

Steps to reproduce the bug

1. Modify the display scale
2. UIElement.RasterizationScale doesn't change

Expected behavior

I assume, since documentation of the two properties is exactly the same, that they would behave the same.

Screenshots

NuGet package version

WinUI 3 - Windows App SDK 1.5.3: 1.5.240428000

Windows version

Windows 11 (22H2): Build 22621

Additional context

I noticed this while I was implementing a custom tile bar with a text box according to this article. I forgot two use titleBar.XamlRoot.RasterizationScale and instead used titleBar.RasterizationScale.

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[codendone]

The documentation for UIElement.RasterizationScale is incorrect. Here's the description from when this property was added:

This API lets Xaml create its shape masks, decode images, and play media at a higher resolution than normal. It's meant to be multiplied into the transforms that we've already accumulated in the render walk.

I agree it is confusing that this property has the same name as XamlRoot.RasterizationScale but has this different behavior. We should verify if a documentation change is sufficient or if a design change may be desired.