I had previously viewed this presentation. The presentation states that the What's New section of the ObjectARX documentation reviews all of the new extension classes. In fact the What's New section lists only the DocumentExtension class.
I was able to find the GetAcadDocument function in the DocumentExtension class. This function apparently wraps an ObjectARX class which isn't named (searching the ObjectARX SDK for that name comes up with nothing). This function returns an Object.
As with previous versions the class AcadDocument isn't documented but the acadi.h file lists the functions available including Regen which accepts one arguement which can be either acActiveViewport = 0 or acAllViewports = 1.
Dim AcadDoc As Object
AcadDoc = GetAcadDocument(DocumentManager.MdiActiveDocument)
I was able to find the window extension by guessing at its location and the following functions should provide the correct information.
Dim AcadTopLeft, AcadMid As System.Drawing.Point
Dim AcadSize As System.Drawing.Size
AcadTopLeft = GetLocation(Application.MainWindow)
AcadSize = GetSize(Application.MainWindow)