How to change docking icon during run time in WinForms Docking Manager?

private void button1_Click(object sender, System.EventArgs e)
{
    //Here we Change the Docking Manager ImageList property from
    //ImageList1 to ImageList2 by alternatively
    if(dockingManager1.ImageList==this.imageList2)
       dockingManager1.ImageList=this.imageList1;
    else
       dockingManager1.ImageList=this.imageList2;
}
//Occurs when the ImageList property changes
private void dockingManager1_ImageListChanged(object sender, System.EventArgs e)
{
    //Here the code which set the Docking Icon dynamically.
    dockingManager1.SetDockIcon(this.panel1,0);
    dockingManager1.SetDockIcon(this.panel2,1);
}

Private Sub button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles button1.Click
     'Here we Change the Docking Manager ImageList property from
     'ImageList1 to ImageList2 by alternatively
     If dockingManager1.ImageList Is Me.imageList2 Then
        dockingManager1.ImageList=Me.imageList1
     Else
        dockingManager1.ImageList=Me.imageList2
     End If
End Sub
'Occurs when the ImageList property changes
Private Sub dockingManager1_ImageListChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles dockingManager1.ImageListChanged
     'Here the code which set the Docking Icon dynamically.
     dockingManager1.SetDockIcon(Me.panel1,0)
     dockingManager1.SetDockIcon(Me.panel2,1)
End Sub