private void BtnDB_Click(object sender, RoutedEventArgs e)
        {
            SetFocusToEqualsButton();
            DbPreviewWindow dbPreview = new DbPreviewWindow();

            dbPreview.ShowDialog();
        }
        void System.Windows.Markup.IComponentConnector.Connect(int connectionId, object target)
        {
            switch (connectionId)
            {
            case 1:
                this.DbPreviewWindowForm = ((Calculator.DbPreviewWindow)(target));
                return;

            case 2:
                this.listViewPreview = ((System.Windows.Controls.ListView)(target));
                return;
            }
            this._contentLoaded = true;
        }