Provides the ability add or open a project item with a specific editor and to transfer an item to another project, in addition to the methods in the IVsProject2 interface.
Transfers an item from one project to another. The project that presently owns the item to be transferred calls this method on the project intending to receive the transferred item.
Notes to Implementers:
Implement IVsProject3 when needing to add or open items or documents in a project using a specific editor, or to transfer an item between projects.