VB.net WPF访问应用程序启动中调用的变量

Question

我正在编写一个程序，它在应用程序的启动事件处理程序中启动一个Excel文件：

' Application.xaml.vb
Imports Microsoft.Office.Interop

Class Application
    ' Application-level events, such as Startup, Exit, and DispatcherUnhandledException
    ' can be handled in this file.

    ' Startup handler
    Public Sub Application_Startup(sender As Object, e As StartupEventArgs) Handles Me.Startup
        ' Initialise Excel
        Dim XLapp As Excel.Application
        Dim XLwb As Excel.Workbook
        Dim XLws As Excel.Worksheet
        Dim XLra As Excel.Range
        ' File and worksheet are opened here, using inputprompt to query user for the right sheet.
    End Sub
End Class

现在我的问题是，如何从MainWindow.xaml.vb访问这些变量（如XLws）？通常你会创建一个类的新对象，但这是否适用于应用程序的启动处理程序？如果是这样，我如何解决发件人和e参数错误？

我想要的是应用程序在启动时加载大型excel文件，然后在button_clicks上读取/写入它。