Pmw Group using grid

[Irene Barg]

Hi,
I want to use the Pmw.Group widget, but I want to use the grid 
geometry manager.  I can't get the group widget to expand 
horizontally to fit the parent widget. Example below:

self.megaTop = Pmw.MegaToplevel(parent,title=self.title)
self.interior = self.megaTop.interior()
self.sf = Pmw.ScrolledFrame(self.interior,hull_width=600,
    hull_height=200)
self.sframe = self.sf.interior()
self.sf.pack(padx = 5, pady = 5, fill = 'both', expand = 1)
resultgrp = Pmw.Group(self.sframe,hull_width=600)
resultgrp.grid(row=rn,column=0,sticky='EW',padx=2,pady=2)

When the Pmw.Group object is displayed, it's centered inside
the 'sframe'.  I can't make it expand to the width of the
ScrolledFrame.  I don't want to use 'pack', because I want
to use the Pmw.Group object as a 'record' holder, then
place it inside a 'loop' so that the Next/Prev record gets
re-written.  Is their some subtle syntax in Pmw I'm missing?

Your comments are appreciated.
--irene barg