What we ideally need is, to know how Microsoft handles XAML generated code (Those *.g.cs files). If you goto a XAML code behind, intellisense will work even if the *.g.cs file is not part of the project!!
Context:
In a custom VS package, we need to have some logic to open a CS file (with out making it a part of the project) in the VS IDE, to allow the user to edit it.
We are hooking up the document to the Running document table and receiving the events like Saving, Close and all, using IVSRunningDocumentTable. Works good.
Now the problem is, when the document is opened, Intellisense can't work, for the simple reason that the opened document is not part of the project (sadly, we can't do that, we can't make it code behind).