public override bool IsValidStartupItem(IProjectItem projectItem) { if (this.IsControlLibrary) { return(base.IsValidStartupItem(projectItem)); } ProjectXamlContext projectContext = ProjectXamlContext.GetProjectContext((IProject)this); if (projectItem != null && projectContext != null) { IProjectDocument document = projectContext.GetDocument(DocumentReferenceLocator.GetDocumentLocator(projectItem.DocumentReference)); if (document != null && document.DocumentType == ProjectDocumentType.Page) { return(true); } } return(false); }