How to replace the default +/- expand buttons with the customized image buttons when the records are grouped WinForms in the GridGroupingControl?

//CellModel. 
public class GridPushButtonImageCellModel: GridPushButtonCellModel
{
    protected GridPushButtonImageCellModel(SerializationInfo info, StreamingContext context) : base(info, context){}
    public GridPushButtonImageCellModel(GridModel grid) : base(grid){}
    public override GridCellRendererBase CreateRenderer(GridControlBase control)
    {
        return new GridPushButtonImageCellRenderer(control, this);
    }
}

Public Class GridPushButtonImageCellModel
    Inherits GridPushButtonCellModel
    Protected Sub New(ByVal info As SerializationInfo, ByVal context As StreamingContext)
       MyBase.New(info, context)
    End Sub
    Public Sub New(ByVal grid As GridModel)
        MyBase.New(grid)
    End Sub
    Public Overrides Function CreateRenderer(ByVal control As GridControlBase) As GridCellRendererBase
        Return New GridPushButtonImageCellRenderer(control, Me)
    End Function
End Class

//CellRenderer
public class GridPushButtonImageCellRenderer : GridPushButtonCellRenderer
{
    private ImageCellButton pushButton;
    public GridPushButtonImageCellRenderer(GridControlBase grid, GridPushButtonImageCellModel cellModel) : base(grid, cellModel)
   {
        base.RemoveButton(base.GetButton(0));
        AddButton(pushButton = new ImageCellButton(this));
   }
}

'CellRenderer.
Public Class GridPushButtonImageCellRenderer
    Inherits GridPushButtonCellRenderer
    Private pushButton As ImageCellButton = New ImageCellButton(Me)
    Public Sub New(ByVal grid As GridControlBase, ByVal cellModel As GridPushButtonImageCellModel)
        MyBase.New(grid, cellModel)
        MyBase.RemoveButton(MyBase.GetButton(0))
        AddButton(pushButton)
    End Sub
End Class

//ImageCellButton.
public class ImageCellButton : GridCellButton
{
    static GridIconPaint iconPainter;
    static ImageCellButton()
    {
       iconPainter = new GridIconPaint("ImagePushButton.", typeof(ImageCellButton).Assembly);
    }
    public ImageCellButton(GridPushButtonCellRenderer control) : base(control)
    {
        Console.WriteLine("In ImageCellButton");
    }
    public override void Draw(Graphics g, int rowIndex, int colIndex, bool bActive, GridStyleInfo style)
    {
         base.Draw(g, rowIndex, colIndex, bActive, style);
         //Draws the button.
         bool hovering = IsHovering(rowIndex, colIndex);
         bool mouseDown = IsMouseDown(rowIndex, colIndex);
         bool disabled = !style.Clickable;
         ButtonState buttonState = ButtonState.Normal;
         if(disabled)
  buttonState |= ButtonState.Inactive|ButtonState.Flat;
         else if (!hovering && !mouseDown)
  buttonState |= ButtonState.Flat;
  Point ptOffset = Point.Empty;
  if(mouseDown)
  {
     ptOffset = new Point(1, 1);
     buttonState |= ButtonState.Pushed;
  }
  DrawButton(g, Bounds, buttonState, style);
            Image img = Image.FromFile(Application.StartupPath + "..\\..\\..\\Browse.bmp");
            Bitmap bmp = img as Bitmap;
            Rectangle r = iconPainter.PaintIcon(g, Bounds, ptOffset, bmp, Color.Black);
     }
}

'ImageCellButton.
Public Class ImageCellButton
    Inherits GridCellButton
    Private Shared iconPainter As GridIconPaint
       Shared Sub New()
       iconPainter = New GridIconPaint("ImagePushButton.", GetType(ImageCellButton).Assembly)
    End Sub
    Public Sub New(ByVal control As GridPushButtonCellRenderer)
        MyBase.New(control)
        Console.WriteLine("In ImageCellButton")
    End Sub
    Public Overrides Sub Draw(ByVal g As Graphics, ByVal rowIndex As Integer, ByVal colIndex As Integer, ByVal bActive As Boolean, ByVal style As GridStyleInfo)
        MyBase.Draw(g, rowIndex, colIndex, bActive, style)
        'Draws the button.
        Dim hovering As Boolean = IsHovering(rowIndex, colIndex)
        Dim mouseDown As Boolean = IsMouseDown(rowIndex, colIndex)
        Dim disabled As Boolean = Not style.Clickable
        Dim buttonState As ButtonState = ButtonState.Normal
        If disabled Then
 buttonState = buttonState Or ButtonState.Inactive Or ButtonState.Flat
        ElseIf (Not hovering) AndAlso (Not mouseDown) Then
 buttonState = buttonState Or ButtonState.Flat
        End If
        Dim ptOffset As Point = Point.Empty
        If mouseDown Then
 ptOffset = New Point(1, 1)
 buttonState = buttonState Or ButtonState.Pushed
        End If
        DrawButton(g, Bounds, buttonState, style)
        Dim img As Image = Image.FromFile(Application.StartupPath & "..\..\..\Browse.bmp")
        Dim bmp As Bitmap = TryCast(img, Bitmap)
        Dim r As Rectangle = iconPainter.PaintIcon(g, Bounds, ptOffset, bmp, Color.Black)
End Sub

//Adds the ImagePushButton Model in the GridGroupingControl CellModel.
this.gridGroupingControl1.TableModel.CellModels.Add("ImagePushButton", new GridPushButtonImageCellModel(this.gridGroupingControl1.TableModel));

'Adds the ImagePushButton Model in the GridGroupingControl CellModel.
Me.gridGroupingControl1.TableModel.CellModels.Add("ImagePushButton", New GridPushButtonImageCellModel(Me.gridGroupingControl1.TableModel))

//Loads image in the GroupExpander used in grouping cases.
this.gridGroupingControl1.TableDescriptor.Appearance.GroupCaptionPlusMinusCell.CellType = "ImagePushButton";
//Loads image in the RecordExpander used in nestedgrid cases.
this.gridGroupingControl1.TableDescriptor.Appearance.RecordPlusMinusCell.CellType = "ImagePushButton";

'Loads image in the GroupExpander used in grouping cases.
Me.gridGroupingControl1.TableDescriptor.Appearance.GroupCaptionPlusMinusCell.CellType = "ImagePushButton"
'Loads image in the RecordExpander used in nestedgrid cases.
Me.gridGroupingControl1.TableDescriptor.Appearance.RecordPlusMinusCell.CellType = "ImagePushButton"