void ShowPreviewDialogButton_Click (object sender, EventArgs e)
{
PrintPreviewDialog ppd = new PrintPreviewDialog ();
ppd.ClientSize = new Size (400, 300);
ppd.Location = new Point (29, 29);
ppd.MinimumSize = new Size (375, 250);
ppd.UseAntiAlias = true;
ppd.Document = new MyPrintDocument ();
ppd.ShowDialog ();
}