private void cmbPrinter_SelectedIndexChanged(object sender, EventArgs e)
{
this.printerError.Clear();
this.cmbPaper.DataSource = null;
if (this.cmbPrinter.Text == string.Empty)
{
return;
}
this.cmbPaper.DataSource = printerHelper.getPaperNameList(this.cmbPrinter.Text);
}