how to add close button to my tab button

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C#

ASP.NET

Hi,
i use a treeview in my code and when i click on childnode, a button is created as a tab with selected node value as its text.i want to add close button to every button created.
this is my code:

<style type="text/css">
    .Initial
 {
   direction:rtl;
   display: block;
   padding: 4px 18px 4px 18px;
   float: right;
   background: url("InitialImage.png") no-repeat right top;
   color: Black;
   font-weight: bold;
 }
 .Initial:hover
 {
   direction:rtl;
   color: White;
   background: url("InitialImage.png") no-repeat right top;
 }
 .Clicked
 {
     direction:rtl;
   float: right;
   display: block;
   background: url("SelectedButton.png") no-repeat right top;
   padding: 4px 18px 4px 18px;
   color: Black;
   font-weight: bold;
   color: White;
 }

public static class Tabbutton
    {
      public static List<Button> myDinamicButtonsListss=new List<Button>();
    }

protected void TreeView1_SelectedNodeChanged(object sender, EventArgs e)
        {
            int flag = 1;
            MainView.Visible = true;
            Button btn = new Button();
            btn.CssClass="Clicked";
            btn.Text = TreeView1.SelectedNode.Value;
            btn.ID = TreeView1.SelectedNode.Target;
            
            foreach (Button b in Tabbutton.myDinamicButtonsListss)
            {
                b.CssClass = "Initial";
            }
            for (int i = 0; i < Tabbutton.myDinamicButtonsListss.Count;i++ )
            {
                if (btn.ID == Tabbutton.myDinamicButtonsListss[i].ID)
                {
                    flag = 0;
                    Tabbutton.myDinamicButtonsListss[i].CssClass = "Clicked";
                    break;
                }
            }
            if (flag == 1)
            {
                btn.CommandArgument = btn.ID;
                btn.Command += new CommandEventHandler(b_Command); //handler
                Tabbutton.myDinamicButtonsListss.Add(btn);
                tabdiv.Controls.Add(btn);
            }
        }