public override async Task<bool> OnOptionsItemSelected(IMenuItem item)
    {
        bool bTotalResult = false;
        switch (item.ItemId)
        {


            case Resource.Id.action_next:
                bTotalResult = await ShowPayMentTypeDialog();

                return await Task.Run(() => true).ConfigureAwait(true); ;
            default:
                return await Task.Run(() => base.OnOptionsItemSelected(item)).ConfigureAwait(true);;
        }
        //return await Task.Run(() => false ).ConfigureAwait(true);
    }
    private async Task<bool> ShowPayMentTypeDialog()
    {
        bool bResult = false;
        try
        {
            LayoutInflater layoutInflater = LayoutInflater.From(this);
            View view = layoutInflater.Inflate(Resource.Layout.lyt_cash_credit_popup, null);
            Android.Support.V7.App.AlertDialog.Builder alertbuilder = new Android.Support.V7.App.AlertDialog.Builder(this);
            alertbuilder.SetView(view);
            var userdata = view.FindViewById<Spinner>(Resource.Id.spnrPaymentTerms);
            List<cls_spinner_adapter> resultsWayNo = new List<cls_spinner_adapter> {
            new cls_spinner_adapter {SZ_SPINNER_TEXT ="CASH"},
           new cls_spinner_adapter {SZ_SPINNER_TEXT ="CREDIT" } };
            CommonSpinnerAdapter paymentAdapter = new CommonSpinnerAdapter(this, resultsWayNo);
            userdata.Adapter = paymentAdapter;
            alertbuilder.SetCancelable(false)
            .SetPositiveButton("OK", delegate
            {
                if (resultsWayNo[userdata.SelectedItemPosition].SZ_SPINNER_TEXT == "CASH")
                {
                    cls_statics.B_IS_PROMOMAYMANET_CASH = true;
                }
                else
                {
                    cls_statics.B_IS_PROMOMAYMANET_CASH = false;
                }
                bResult = true;
            })
            .SetNegativeButton("Cancel", delegate
            {
                cls_statics.B_IS_PROMOMAYMANET_CASH = false;
                bResult = true;
                alertbuilder.Dispose();

            });
            Android.Support.V7.App.AlertDialog dialog = alertbuilder.Create();
            dialog.Show();
        }
        catch
        {

        }
        return await Task.Run(() => bResult).ConfigureAwait(true);
    }

override bool OnOptionsItemSelected

return await Task.Run(() => true)

return true;

//Point 1
public override bool OnOptionsItemSelected(IMenuItem item)
{
    bool bTotalResult = false;

    switch (item.ItemId)
    {
        case Resource.Id.action_next:
            bTotalResult = Task.Run(() => ShowPayMentTypeDialog()).Wait();

            // point 3
            return true;
        default:
            // point 3
            return base.OnOptionsItemSelected(item);
    }
}

// point 4
private bool ShowPayMentTypeDialog()
{
    bool bResult = false;
    try
    {
        LayoutInflater layoutInflater = LayoutInflater.From(this);
        View view = layoutInflater.Inflate(Resource.Layout.lyt_cash_credit_popup, null);
        Android.Support.V7.App.AlertDialog.Builder alertbuilder = new Android.Support.V7.App.AlertDialog.Builder(this);
        alertbuilder.SetView(view);
        var userdata = view.FindViewById<Spinner>(Resource.Id.spnrPaymentTerms);
        List<cls_spinner_adapter> resultsWayNo = new List<cls_spinner_adapter> {
        new cls_spinner_adapter {SZ_SPINNER_TEXT ="CASH"},
       new cls_spinner_adapter {SZ_SPINNER_TEXT ="CREDIT" } };
        CommonSpinnerAdapter paymentAdapter = new CommonSpinnerAdapter(this, resultsWayNo);
        userdata.Adapter = paymentAdapter;
        alertbuilder.SetCancelable(false)
        .SetPositiveButton("OK", delegate
        {
            if (resultsWayNo[userdata.SelectedItemPosition].SZ_SPINNER_TEXT == "CASH")
            {
                cls_statics.B_IS_PROMOMAYMANET_CASH = true;
            }
            else
            {
                cls_statics.B_IS_PROMOMAYMANET_CASH = false;
            }
            bResult = true;
        })
        .SetNegativeButton("Cancel", delegate
        {
            cls_statics.B_IS_PROMOMAYMANET_CASH = false;
            bResult = true;
            alertbuilder.Dispose();

        });
        Android.Support.V7.App.AlertDialog dialog = alertbuilder.Create();
        dialog.Show();
    }
    catch
    {

    }

    // point 3
    return bResult;
}