App: Add SerialPortWatcher

Elwig/Windows/DeliveryAdminWindow.xaml.cs

@@ -1168,6 +1168,19 @@ namespace Elwig.Windows {
             WeighingDButton.IsEnabled = n > 3 && App.CommandScales[3].IsReady;
         }
 
+        public void UpdateScales() {
+            if (!ViewModel.IsReceipt) return;
+            foreach (var s in App.EventScales) {
+                s.WeighingEvent -= Scale_Weighing;
+                s.WeighingEvent += Scale_Weighing;
+            }
+            if (WeighingManualButton.IsEnabled) {
+                EnableWeighingButtons();
+            } else {
+                DisableWeighingButtons();
+            }
+        }
+
         private async Task UpdateLsNr() {
             if (string.IsNullOrEmpty(ViewModel.Date) || ViewModel.Branch == null) {
                 ViewModel.LsNr = "";