private void cmbPaper_SelectedIndexChanged(object sender, EventArgs e)
{
this.paperError.Clear();
DecimalSize size = printerHelper.getPaperSize(cmbPrinter.Text, cmbPaper.Text);
this.txtPaperHeight.Text = size.Height.HasValue ? size.Height.Value.ToString("#.00") : string.Empty;
this.txtPaperWidth.Text = size.Width.HasValue ? size.Width.Value.ToString("#.00") : string.Empty;
}