Selectable GridView with WaitBox

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class _Default : System.Web.UI.Page
{
    #region properties
    /// <summary>
    /// Gets or sets the app mode. It's necessary to distinguish the current state.
    /// Because normally there is an 'click-event' attached to the datagrid. If user 
    /// decide to describe an filter, app mode will be switched to Common.Mode.Describe
    /// and no click-event will be registered.
    /// </summary>
    /// <value>The current application mode.</value>
    public Mode CurrentMode
    {
        get
        {
            object sessionObj = Session[MODE];
            return (sessionObj != null) ? (Mode)sessionObj : Mode.New;
        }
        set { Session[MODE] = value; }
    }
    #endregion

    /// <summary>
    /// Colorize the pop-menu items. Handles the Load event of the LinkBtn control.
    /// </summary>
    /// <param name="sender">The source of the event.</param>
    /// <param name="e">The <see cref="System.EventArgs"/> instance containing the event data.</param>
    protected void LinkBtn_Load(object sender, EventArgs e)
    {
        ((LinkButton)sender).Attributes["onmouseover"] = "this.style.color='Red';";
        ((LinkButton)sender).Attributes["onmouseout"] = "this.style.color='Blue';";
    }


    /// <summary>
    /// On RowDataBound register the java script (click-event) for the grid view.
    /// </summary>
    /// <param name="sender">The sender.</param>
    /// <param name="e">The <see cref="System.Web.UI.WebControls.GridViewRowEventArgs"/> instance containing the event data.</param>
    protected void RegisterJavaScript(object sender, GridViewRowEventArgs e)
    {
        if (CurrentMode != Mode.Describe)
        {
            if (e.Row.RowType == DataControlRowType.DataRow)
            {
                e.Row.Attributes["onmouseover"] = "this.style.cursor='hand';";
                e.Row.Attributes.Add("onclick",
                Page.ClientScript.GetPostBackEventReference((Control)sender, "Select$" + e.Row.RowIndex.ToString()));
            }
        }
    }

    /// <summary>
    /// Register click-event 
    /// </summary>
    /// <param name="writer">The <see cref="T:System.Web.UI.HtmlTextWriter"></see> that receives the page content.</param>
    protected override void Render(HtmlTextWriter writer)
    {
        if (CurrentMode != Mode.Describe)
            for (int i = 0; i < this.gridFilters.Rows.Count; i++)
                ClientScript.RegisterForEventValidation(this.gridFilters.UniqueID, "Select$" + i);
        base.Render(writer);
    }

    /// <summary>
    /// Perform an action depending on selected item.
    /// </summary>
    /// <param name="sender">The source of the event.</param>
    /// <param name="e">The <see cref="System.Web.UI.WebControls.GridViewCommandEventArgs"/> instance containing the event data.</param>
    protected void gridFilters_RowCommand(object sender, GridViewCommandEventArgs e)
    {
        CurrentMode = Mode.New;

        switch (e.CommandName)
        {
            case ("Insert"):
                upMain.Update();
                break;
            case ("Edit"):
                CurrentMode = Mode.Describe;
                break;
        }
    }

    #region variables
    public enum Mode { New, Save, Load, None, Describe };
    public const string MODE = "APPLICATION_MODE";
    #endregion
}