Override MasterPage

[Mark Parter]

I've "converted" the code at http://www.eggheadcafe.com/articles/20040613.asp
to VB.NET as I'd like to implement this as my application uses quite complex
GridViews and various other controls on some pages (viewstate alone was
110Kb+ on some pages!!).

Anyway, I've setup the classes required and created a test page which
inherits from the new BasePage class. It works well. How can I now use this
in an environment that uses mostly Master Pages?

I've tried to create a new MasterPage class which inherits the custom
BasePage class. I've then used this custom MasterPage class in my master page
but I get an error about ContentPlaceholders not being a member of the master
page.

MasterPage.vb
--------------------
Imports Microsoft.VisualBasic

Namespace ServerSideViewstate
Public Class MasterPage
Inherits ServerSideViewstate.BasePage
End Class
End Namespace

layout.master.vb
-----------------------

Partial Class layout
Inherits ServerSideViewstate.MasterPage
End Class