Airdrag modified now has to be set to true or false if it was set in any previous stage

VECTO3GUI2020/ViewModel/MultiStage/Implementation/InterimStageBusVehicleViewModel_v2_8.cs

@@ -72,6 +72,7 @@ namespace VECTO3GUI2020.ViewModel.MultiStage.Implementation
 		private VehicleCode? _vehicleCode;
 		private RegistrationClass? _registeredClass;
 		private bool? _airdragModifiedMultistage;
+		private bool _airdragModifiedEditingEnabled;
 		private LegislativeClass? _legislativeClass;
 		private ConsumerTechnology? _doorDriveTechnology;
 		private TankSystem? _tankSystem;
@@ -226,6 +227,20 @@ namespace VECTO3GUI2020.ViewModel.MultiStage.Implementation
 			set => SetProperty(ref _airdragModifiedMultistage, value);
 		}
 
+		public bool AirdragModifiedMultistageEditingEnabled
+		{
+			get
+			{
+				//IF MODIFIED ONCE IT HAS TO BE SET
+				if (_consolidatedVehicleData.AirdragModifiedMultistage != null) {
+					_airdragModifiedEditingEnabled = true;
+				}
+				return _airdragModifiedEditingEnabled;
+			}
+			set => SetProperty(ref _airdragModifiedEditingEnabled, value);
+		}
+
+
 		public RegistrationClass? RegisteredClass
 		{
 			get => _registeredClass;

VECTO3GUI2020/Views/Multistage/VehicleView_v2_8.xaml

@@ -53,7 +53,8 @@
                                     HideCheckBox="True"/>
 
                 <Separator/>
-                <custom:MultiStageParameter PreviousContent="{Binding ConsolidatedVehicleData.AirdragModifiedMultistage}"
+                <custom:MultiStageParameter EditingEnabled="{Binding AirdragModifiedMultistageEditingEnabled}"
+                    PreviousContent="{Binding ConsolidatedVehicleData.AirdragModifiedMultistage}"
                                     Content="{Binding AirdragModifiedMultistage}" Mode="CHECKBOX"/>
 
                 <custom:MultiStageParameter PreviousContent="{Binding ConsolidatedVehicleData.GrossVehicleMassRating}"