void newshipmentForm_Closed(object sender, EventArgs e)
{
shipmentForm = null;
}
private void BtnShipment_Click(object sender, RoutedEventArgs e)
{
if (shipmentForm == null || shipmentForm.IsActive)
{
shipmentForm = new Shipment();
shipmentForm.Show();
//Add a event handler to set null our window object when it will be closed
shipmentForm.Closed += new EventHandler(newshipmentForm_Closed);
}
//If the window was created and your window isn't active
//we call the method Activate to call the specific window to front
else
{
shipmentForm.Activate();
}
}