Preview 7: Flickery page transitions

Describe the bug Since upgrading from v11 preview 6 to preview 7 I’ve noticed that page transitions are very flickery:

https://user-images.githubusercontent.com/4577868/234988210-0d85f87d-a32a-49f9-be26-1d95a60245fd.mp4

The video is from a quick repro I put together based on the existing routing tutorial: https://github.com/mikegoatly/AvaloniaExperiments

I’ve tried both CrossFade and PageSlide transitions and the flickering is apparent in both.

To Reproduce Steps to reproduce the behavior:

Clone the sample from https://github.com/mikegoatly/AvaloniaExperiments, or create a new project that uses a RoutedViewHost:

<rxui:RoutedViewHost Grid.Row="0" Router="{Binding Router}">
	<rxui:RoutedViewHost.DefaultContent>
		<TextBlock Text="Default content"
						 FontSize="40"
                         HorizontalAlignment="Center"
                         VerticalAlignment="Center" />
	</rxui:RoutedViewHost.DefaultContent>
	<rxui:RoutedViewHost.ViewLocator>
		<!-- See AppViewLocator.cs section below -->
		<app:AppViewLocator />
	</rxui:RoutedViewHost.ViewLocator>
</rxui:RoutedViewHost>

Switch between views and the animations flicker.

Expected behavior The page transitions should be smooth.

Desktop (please complete the following information):

• OS: Windows, also tried in Linux with DRM
• Version 11.0.0-preview7

[kekekeks]

we can’t have two contents at the same time in the content presenter

Well, it means that TransitioningContentControl needs to be changed to have two ContentPresenter instances.

[kekekeks]