Rounded border: corner radius cuts border outline off

Hey, I’m trying to create a borderless window with custom decoration. I decided to use a rounded border for this, for example:

<Border CornerRadius="20"
        BorderBrush="Gray"
        BorderThickness="2"
        ClipToBounds="True">
	<!-- Content -->
</Border>      

Unfortunately, the corner radius cuts the gray border outline off:

Is it possible to outline along the actual (rounded) boundary if a corner radius is set? Also, I noticed that the border edges look really pixelated. Is there a way to enable anti-aliasing for elements with the CornerRadius property in the rendering engine?

Some general system information:

Version	0.10.0-preview6
Host	Arch Linux 5.8.12-arch1-1 (X11)
NET Core SDK	3.1.108

[ThePBone]

Solved it by applying a small padding to the border element content to avoid overlaps with the rounded window border. Here’s my solution if anyone else runs into this issue:

<Border CornerRadius="20"
        BorderBrush="Black"
        BorderThickness="2"
        ClipToBounds="True" Padding="1"
        Background="{DynamicResource SystemControlBackgroundAltHighBrush}">
    
    <DockPanel HorizontalAlignment="Stretch"
               VerticalAlignment="Stretch"
               Name="ContentWrapper"
               Margin="2,0">
        
        <ui:CustomTitleBar Background="Transparent"></ui:CustomTitleBar>
        
        <DockPanel Background="{DynamicResource SystemControlBackgroundAltHighBrush}">
            <!-- Content -->
        </DockPanel>
        
    </DockPanel>
</Border>

[sabuto]

See #6857 (comment)

so i read about a bit and it says to do it in the App Builder like .With(new Win32PlatformOptions { CompositionBackdropCornerRadius = 30}) if that is right it is still not working, is there anything else i need to add?

Also im not sure if it matters but i am also using Material avalonia for styling.