private void BtnAddNew_Click(object sender, RoutedEventArgs e)
{
if (dw2 == null)
{
dw2 = new DW2(vm)
{
Owner = this,
WindowStartupLocation = WindowStartupLocation.CenterOwner
};
dw2.Closed += DW2_Closed;
dw2.Show();
}
}
private void DW2_Closed(object sender, System.EventArgs e) => dw2 = null;