George Jetson?  I think you might be right Mike, but now you're showing your age too!

For the benefit of any future readers of this post I have come up with this function:

Private Function VisibleHeightAbove(ByVal rows As RowsCollection, ByVal fromRow As UltraGridRow, ByRef height As Integer) As Boolean
Dim terminate As Boolean = False
For Each row As UltraGridRow In rows
  If terminate Or row Is fromRow Then
    terminate = True
    Exit For
  End If
  height += row.Height
  If TypeOf row Is UltraGridGroupByRow Then
    Dim groupByRow As UltraGridGroupByRow = row
    If groupByRow.IsExpanded Then
      terminate = VisibleHeightAbove(groupByRow.Rows, fromRow, height)
    End If
  End If
Next
Return terminate
End Function

This can then be called from the grid control's AfterRowRegionScroll event like this:

Private Sub UltraGrid1_AfterRowRegionScroll(ByVal sender As Object, ByVal e As RowScrollRegionEventArgs) Handles UltraGrid1.AfterRowRegionScroll
If e.RowScrollRegion.VisibleRows.Count > 0 Then
  Dim spaceAbove As Integer = 0
  Dim firstVisibleRow As UltraGridRow = e.RowScrollRegion.VisibleRows(0).Row
  If firstVisibleRow IsNot Nothing Then
    VisibleHeightAbove(UltraGrid1.Rows, firstVisibleRow, spaceAbove)
  End If
  'Then do what you want with "spaceAbove"
End If
End Sub

 BTW.. isn't Mr. Jetson's first name George? :)