create a custom task pane that users can hide or display by clicking a toggle button on the Ribbon

Hi aravind,
From visual studio 2008 you can easily create a custom task pane

1. Create Excel/Word Add-In Project
2. Add a user control (UserControl1.cs) to the project
3. Open ThisAddIn.cs project
4. Add the following code

using   Microsoft.Office.Tools;
namespace ExcelAddInCustomTab
{
    public partial class ThisAddIn
    {

        public CustomTaskPane ctp;
        private void ThisAddIn_Startup(object sender, System.EventArgs e)
        {
            UserControl1 TPControl = new UserControl1();
            ctp = CustomTaskPanes.Add(TPControl, "my CTP");
            ctp.Visible = true;
        }



    }
}

And also Add the following code in toggle Button click event for hiding and displaying Custom Task Pane

 private void button1_Click(object sender, RibbonControlEventArgs e)
        {
            Globals.ThisAddIn.ctp.Visible = !Globals.ThisAddIn.ctp.Visible;
        }