Get DefaultLanguage of Windows Store project

Hi

I am the author of an Add-In so support the localization of projects in visual studio. I am extending this tool to support Windows Store projects. This will probably be the first of many questions. :-)

I want to get hold of the DefaultLanguage property.

In the UI, you can enter this via the Package.appxmanifest file. I have already discovered that the property is actually stored in the project file (e.g. .csproj) so the UI is misleading.

I have already looked in the properties collection of the EnvDTE.Project, but I didn't find it.

So how can I get the DefaultLanguage property from an Add-In?

Thanks in advance
Phil