GridView - A wrong PageIndex appears in Action parameters when the grid is used in Custom Binding mode

[DX Support team: this thread was cloned from GridView - Сustom databinding issues]
Hello,

I'm trying the new custom binding mode on gridviews and I have several problems implementing it.
I try do display several objects which contain other objects. Here is a simplified example of what my objects looks like :

C#
public class Car  
{  
    public int id;  
    public Engine engine;  
    public string model;  
    public string brand;  
}  

public class Engine  
{  
    public int id;  
    public string brand;  
    public string model;  
    public int horsePower;  
}  

My second problem is when I try to go to the other pages of the gridview. When my controller paging action is called, the StartDataRowIndex of the GridViewPagerState is always 0. Do you have any clue on what could cause this behavior?
Thanks.
Here is my controller code :

C#
public class CarController : Controller  
{  
    [HttpGet, ActionName(CarControllerAction.Car)]  
    public ActionResult Car()  
    {  
        return View(CarControllerAction.Car);  
    }  

    [AcceptVerbs(HttpVerbs.Get | HttpVerbs.Post), ActionName(CarControllerAction.Car_Partial)]  
    public PartialViewResult Car_Partial()  
    {  
        var viewModel = GridViewExtension.GetViewModel("gvCar");  
        if (viewModel == null)  
        {  
            viewModel = new GridViewModel();  
            viewModel.KeyFieldName = "ID";  

            viewModel.Columns.Add("ID");  
            viewModel.Columns.Add("Model");  
            viewModel.Columns.Add("Brand"); viewModel.Columns.Add("Engine.ID");  
            viewModel.Columns.Add("Engine.Brand");  
            viewModel.Columns.Add("Engine.Model");  
            viewModel.Columns.Add("Engine.HorsePower");  
        }  

        viewModel.ProcessCustomBinding(  
            MyBindingHandlers.MyGetDataRowCount,  
            MyBindingHandlers.MyGetData);  

        return PartialView(CarControllerAction.Car_Partial, viewModel);  
    }  

    [AcceptVerbs(HttpVerbs.Get | HttpVerbs.Post), ActionName(CarControllerAction.Car_Partial_Paging)]  
    public PartialViewResult Car_Partial_Paging(GridViewPagerState pager)  
    {  
        var viewModel = GridViewExtension.GetViewModel("gvCar");  
        viewModel.Pager.Assign(pager); // pager.PageIndex is always 0 ???!!!  
        viewModel.ProcessCustomBinding(  
            MyBindingHandlers.MyGetDataRowCount,  
            MyBindingHandlers.MyGetData);  
        return PartialView(CarControllerAction.Car_Partial, viewModel);  
    }  
}  



public class CarControllerAction  
{  
    public const string Car = "Car";  
    public const string Car_Partial = "Car_Partial";  
    public const string Car_Partial_Paging = "Car_Partial_Paging";  
}  



public static class MyBindingHandlers {  
    static IQueryable<Car> Model { get { return new CarDAO<Car>().GetAll_Query(); } }  

    public static void MyGetDataRowCount(GridViewCustomBindingGetDataRowCountArgs e) {  
        e.DataRowCount = Model.Count();  
    }  

    public static void MyGetData(GridViewCustomBindingGetDataArgs e) {  
        e.Data = Model  
            .Skip(e.StartDataRowIndex)  
            .Take(e.DataRowCount)  
            .ToList();  
    }  
}  

And here is my view :

C#
@model GridViewModel  

@Html.DevExpress().GridView(  
    settings =>  
    {  
        settings.Name = "gvCar";  

        settings.CallbackRouteValues = new {  
            Controller = "CarController",  
            Action = CarControllerAction.Car_Partial  
        };  
        settings.CustomBindingRouteValuesCollection.Add(  
            GridViewOperationType.Paging,  
            new {  
                Controller = "CarController",  
                Action = CarControllerAction.Car_Partial_Paging  
            }  
        );  

        settings.KeyFieldName = "ID";  
        settings.Width = System.Web.UI.WebControls.Unit.Percentage(100);  
        settings.Settings.ShowColumnHeaders = true;  
        settings.Settings.ShowFilterRow = true;  
        settings.Settings.ShowFilterRowMenu = true;  
        settings.Settings.ShowFooter = true;  
        settings.Settings.ShowGroupButtons = true;  
        settings.Settings.ShowGroupedColumns = true;  
        settings.Settings.ShowGroupPanel = true;  
        settings.Settings.ShowHeaderFilterButton = true;  
        settings.Settings.ShowTitlePanel = true;  
        settings.Settings.UseFixedTableLayout = true;  



        settings.SettingsBehavior.AllowDragDrop = true;  
        settings.SettingsBehavior.AllowFocusedRow = true;  
        settings.SettingsBehavior.AllowGroup = true;  
        settings.SettingsBehavior.AllowSort = true;  
        settings.SettingsBehavior.ColumnResizeMode = ColumnResizeMode.NextColumn;  
        settings.SettingsBehavior.ConfirmDelete = true;  
        settings.SettingsBehavior.EnableRowHotTrack = true;  



        settings.SettingsPager.FirstPageButton.Visible = true;  
        settings.SettingsPager.LastPageButton.Visible = true;  
        settings.SettingsPager.PageSize = 50;  
        settings.SettingsPager.PageSizeItemSettings.Visible = true;  
        settings.SettingsPager.PageSizeItemSettings.Items = new string[] { "10", "20", "50" };  



        settings.SettingsCookies.Enabled = true;  
        settings.SettingsCookies.CookiesID = settings.Name;  
        settings.SettingsCookies.StoreColumnsVisiblePosition = true;  
        settings.SettingsCookies.StoreColumnsWidth = true;  
        settings.SettingsCookies.StoreFiltering = true;  
        settings.SettingsCookies.StoreGroupingAndSorting = true;  
        settings.SettingsCookies.StorePaging = true;  



        settings.SettingsBehavior.EnableCustomizationWindow = true;  
        settings.SettingsPopup.CustomizationWindow.Height = 500;  
        settings.SettingsPopup.CustomizationWindow.Width = 250;  

        settings.Columns.Add(column => {  
            column.FieldName = "ID";  
            column.ColumnType = MVCxGridViewColumnType.TextBox;});  
        settings.Columns.Add(column => {  
            column.FieldName = "Model";  
            column.ColumnType = MVCxGridViewColumnType.TextBox;});  
        settings.Columns.Add(column => {  
            column.FieldName = "Brand";  
            column.ColumnType = MVCxGridViewColumnType.TextBox;});  
        settings.Columns.Add(column => {  
            column.FieldName = "Engine.ID";  
            column.ColumnType = MVCxGridViewColumnType.TextBox;});  
        settings.Columns.Add(column => {  
            column.FieldName = "Engine.Brand";  
            column.ColumnType = MVCxGridViewColumnType.TextBox;});  
        settings.Columns.Add(column => {  
            column.FieldName = "Engine.Model";  
            column.ColumnType = MVCxGridViewColumnType.TextBox;});  
        settings.Columns.Add(column => {  
            column.FieldName = "Engine.HorsePower";  
            column.ColumnType = MVCxGridViewColumnType.TextBox;});  
    }  
).BindToCustomData(Model).GetHtml()