' This method initializes an individual ToolStripButton
' control. It copies a subimage from the GridStripRenderer's
' main image, according to the position and size of 
' the ToolStripButton.
Protected Overrides Sub InitializeItem(item As ToolStripItem)
   MyBase.InitializeItem(item)
   
      Dim gs As GridStrip = item.Owner
   
   ' The empty cell does not receive a subimage.
      If ((TypeOf (item) Is ToolStripButton) And _
           (item IsNot gs.EmptyCell)) Then
          ' Copy the subimage from the appropriate 
          ' part of the main image.
          Dim subImage As Bitmap = bmp.Clone(item.Bounds, PixelFormat.Undefined)

          ' Assign the subimage to the ToolStripButton
          ' control's Image property.
          item.Image = subImage
      End If
End Sub