private void AddVendor()
{
AddModifyVendorWindow amvw = new AddModifyVendorWindow(null);
amvw.Show();
this.Close();
}
private void ModifyVendor()
{
AddModifyVendorWindow amvw = new AddModifyVendorWindow((List<Vendor>)vendorViewSource.Source);
amvw.Show();
this.Close();
}