private void InitializeFilterView(FilterView filterview)
        {
            var okButton = FindControl.FindChild <Button>(filterview, "btnOk");

            okButton.Click += OnPopupButtonClick;

            var cancelButton = FindControl.FindChild <Button>(filterview, "btnCancel");

            cancelButton.Click += OnPopupButtonClick;

            var clearButton = FindControl.FindChild <Button>(filterview, "btnClear");

            clearButton.Click += OnPopupButtonClick;

            filterview.LostFocus -= PopLostFocus;
            filterview.LostFocus += PopLostFocus;
            filterview.Focus();
            filterview.UpdateLayout();
        }