use x11 backend test builds.
MODIFY
Directory.Build.targets
Directory.Build.targets
<Project>
<PropertyGroup>
- <AvaloniaVersion>0.7.1-build1011-beta</AvaloniaVersion>
+ <AvaloniaVersion>0.7.1-build1174-beta</AvaloniaVersion>
<AvaloniaBehaviorsVersion>0.7.0</AvaloniaBehaviorsVersion>
</PropertyGroup>

MODIFY
nuget.config
nuget.config
<packageSources>
<add key="nuget.org" value="https://www.nuget.org/api/v2/" />
<add key="AvaloniCI" value="https://www.myget.org/F/avalonia-ci/api/v2" />
+ <add key="Avalonia-PRS" value="https://www.myget.org/F/avalonia-prs/api/v2" />
<add key="XamlBehaviors" value="https://www.myget.org/F/xamlbehaviors-nightly/api/v2" />
<add key="DockNightly" value="https://www.myget.org/F/dock-nightly/api/v2" />
</packageSources>

use x11 backend test builds.