Fix for XAF selection box which does not deselect after clearing the selection.

MyClass.cs

using System;
using System.Web.UI;
using System.Web.UI.WebControls;
using DevExpress.ExpressApp;
using DevExpress.ExpressApp.Templates;
using DevExpress.ExpressApp.Utils;
using DevExpress.ExpressApp.Web;
using DevExpress.ExpressApp.Web.Editors.ASPx;
using DevExpress.ExpressApp.Web.Templates;
using DevExpress.Web.ASPxEditors;
using DevExpress.Web.ASPxGridView;
using NetModule.Controllers;

namespace MyModule.Web
{
    public class MyClass : ViewController<ListView>
    {
        private ISupportViewChanged template;
        protected override void OnActivated()
        {
            base.OnActivated();
            template = Frame.Template as ISupportViewChanged;
            if (template != null)
            {
                template.ViewChanged += new EventHandler<TemplateViewChangedEventArgs>(MyClass_ViewChanged);
            }
        }
        protected override void OnDeactivated()
        {
            if (template != null)
            {
                template.ViewChanged -= new EventHandler<TemplateViewChangedEventArgs>(MyClass_ViewChanged);
            }
            base.OnDeactivated();
        }
        void MyClass_ViewChanged(object sender, TemplateViewChangedEventArgs e)
        {
            ASPxGridListEditor editor = View.Editor as ASPxGridListEditor;
            if (editor != null && editor.Grid != null)
            {
                if (editor.Grid.Parent != null & editor.Grid.Page != null)
                {
                    foreach (GridViewColumn column in editor.Grid.Columns)
                    {
                        if (column is XafGridViewCommandColumn & column.HeaderTemplate != null & column.HeaderTemplate is SelectionColumnHeaderTemplate)
                        {
                            SelectionColumnHeaderTemplate selectionColumnHeaderTemplate = column.HeaderTemplate as SelectionColumnHeaderTemplate;
                            if (selectionColumnHeaderTemplate != null)
                                selectionColumnHeaderTemplate.Dispose();
                            column.HeaderTemplate = new FixedSelectionColumnHeaderTemplate();
                        }
                    }
                }
            }
        }
    }

    public class FixedSelectionColumnHeaderTemplate : ITemplate, IDisposable
    {
        public const string SelectAllCommandName = "SelectAll";
        public const string UnselectAllCommandName = "UnselectAll";
        private ASPxCheckBox selectAll;
        private GridViewHeaderTemplateContainer templateContainer;
        private bool delayedLoadPostData;
        private void TryLoadPostDataToCheckBox()
        {
            if (selectAll.Page != null)
            {
                TryLoadPostData();
            }
            else
            {
                delayedLoadPostData = true;
            }
        }
        private XafCallbackManager CallbackManager
        {
            get
            {
                Page page = GridControl != null ? GridControl.Page : null;
                Guard.ArgumentNotNull(page, "Page");
                Guard.TypeArgumentIs(typeof(ICallbackManagerHolder), page.GetType(), "Page");
                return ((ICallbackManagerHolder)page).CallbackManager;
            }
        }
        private ASPxGridView GridControl
        {
            get { return templateContainer != null ? templateContainer.Grid : null; }
        }
        private void selectAll_Load(object sender, EventArgs e)
        {
            selectAll.Load -= new EventHandler(selectAll_Load);
            string clientScript = CallbackManager.GetScript(GridControl.UniqueID, string.Format("s.GetChecked() ? '{0}' : '{1}'", SelectAllCommandName, UnselectAllCommandName));
            selectAll.ClientSideEvents.CheckedChanged = string.Format(@"function(s, e) {{ {0} }}", clientScript);

            // Is this the part to comment out Dennis?
            //if (delayedLoadPostData)
            //{
            //    TryLoadPostData();
            //    delayedLoadPostData = false;
            //}
        }
        private void TryLoadPostData()
        {
            if (System.Web.HttpContext.Current.Request.Params[selectAll.UniqueID] != null)
            {
                ((IPostBackDataHandler)selectAll).LoadPostData(selectAll.UniqueID, System.Web.HttpContext.Current.Request.Params);
            }
        }
        public ASPxCheckBox SelectAll
        {
            get
            {
                return selectAll;
            }
        }
        #region ITemplate Members
        public void InstantiateIn(Control container)
        {
            templateContainer = (GridViewHeaderTemplateContainer)container;
            Panel panel = new Panel();
            panel.HorizontalAlign = HorizontalAlign.Center;
            container.Controls.Add(panel);
            selectAll = RenderHelper.CreateASPxCheckBox();
            selectAll.ID = "SCh";
            selectAll.EnableClientSideAPI = true;
            selectAll.AutoPostBack = false;
            selectAll.Load += new EventHandler(selectAll_Load);
            panel.Controls.Add(selectAll);
            TryLoadPostDataToCheckBox();
        }
        #endregion
        #region IDisposable Members
        public void Dispose()
        {
            if (selectAll != null)
            {
                selectAll.Load -= new EventHandler(selectAll_Load);
                selectAll.Dispose();
                selectAll = null;
            }
        }
        #endregion
    }
}