DataGrid VScrollBar Bug?

[bleedledeep]

I have a DataGrid that ends up with a VScrollBar due to the number of
rows, and the behavior I want is for the bottom-most row of the
DataGrid to be shown, i.e., I want the VScrollBar all the way to the
bottom (maximum).

I grab and set the VScrollBar using the following:

if ( historyDataGrid.Controls[1] is VScrollBar )
{
VScrollBar vsb = (VScrollBar)historyDataGrid.Controls[1];
vsb.Value = vsb.Maximum;
}

This ALMOST works. The VScrollBar moves to the bottom, but the
DataGrid is scrolled only to about 99.5% of maximum. A mouse click to
the sliderbar or the small-increment button causes the DataGrid to be
scrolled all the way to the bottom. I have tried all sorts of stuff -
I'm almost ready to fake a mouse click, but that just seems waaayyyy
too ugly.

Any help greatly appreciated.