BaseDataWindow: Fix Modifier creation

Elwig/Windows/AdministrationWindow.cs

@@ -462,6 +462,10 @@ namespace Elwig.Windows {
             InputTextChanged((TextBox)sender, Validator.CheckInteger);
         }
 
+        protected void DecimalInput_TextChanged(object sender, RoutedEventArgs evt) {
+            InputTextChanged((TextBox)sender, Validator.CheckDecimal);
+        }
+
         protected void PartialDateInput_TextChanged(object sender, RoutedEventArgs evt) {
             InputTextChanged((TextBox)sender, Validator.CheckPartialDate);
         }