Public Function GetViewportRectangle( _
   ByVal rowViewportIndex As Integer, _
   ByVal columnViewportIndex As Integer _
) As Rectangle

Dim instance As SpreadView
Dim rowViewportIndex As Integer
Dim columnViewportIndex As Integer
Dim value As Rectangle
 
value = instance.GetViewportRectangle(rowViewportIndex, columnViewportIndex)

public Rectangle GetViewportRectangle( 
   int rowViewportIndex,
   int columnViewportIndex
)