My initial answer tried to work for my development setup, but did not work on our installation setup, because for some reason it did not include the XULRunner files inside the web package created using MSDeploy. I found what seems like a simpler installation, below:
<ItemGroup> <Content Include="XULRunner\**\*.*"> <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory> </Content> </ItemGroup>
I'm not 100% sure if this works all over the place, but it seems to work better in every development and deployment scheme I've encountered so far.
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