diff --git a/NTwain.Net35/NTwain.Net35.csproj b/NTwain.Net35/NTwain.Net35.csproj
index 4d6bd4b..f54b7a1 100644
--- a/NTwain.Net35/NTwain.Net35.csproj
+++ b/NTwain.Net35/NTwain.Net35.csproj
@@ -153,6 +153,9 @@
     <Compile Include="..\NTwain\Properties\VersionInfo.cs">
       <Link>Properties\VersionInfo.cs</Link>
     </Compile>
+    <Compile Include="..\NTwain\ProtocolVersions.cs">
+      <Link>ProtocolVersions.cs</Link>
+    </Compile>
     <Compile Include="..\NTwain\SourceEnableMode.cs">
       <Link>SourceEnableMode.cs</Link>
     </Compile>
diff --git a/NTwain/CapWrapper.cs b/NTwain/CapWrapper.cs
index c706bfe..98f5907 100644
--- a/NTwain/CapWrapper.cs
+++ b/NTwain/CapWrapper.cs
@@ -15,10 +15,11 @@ namespace NTwain
     /// <typeparam name="TValue">The TWAIN type of the value.</typeparam>
     public class CapWrapper<TValue> : NTwain.ICapWrapper<TValue>
     {
-        ICapControl _source;
+        IDataSource _source;
         Func<object, TValue> _getConvertRoutine;
         Func<TValue, ReturnCode> _setCustomRoutine;
         Func<TValue, TWOneValue> _setOneValueFunc;
+        bool _readOnly;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="CapWrapper{TValue}" /> class.
@@ -31,16 +32,18 @@ namespace NTwain
         /// or
         /// getConversionRoutine
         /// </exception>
-        public CapWrapper(ICapControl source, CapabilityId capability,
-            Func<object, TValue> getConversionRoutine)
+        public CapWrapper(IDataSource source, CapabilityId capability,
+            Func<object, TValue> getConversionRoutine, bool readOnly)
         {
             if (source == null) { throw new ArgumentNullException("source"); }
             if (getConversionRoutine == null) { throw new ArgumentNullException("getConversionRoutine"); }
 
             _source = source;
             _getConvertRoutine = getConversionRoutine;
+            _readOnly = readOnly;
             Capability = capability;
-            SupportedActions = source.CapQuerySupport(capability);
+
+            CheckSupports();
         }
 
 
@@ -58,7 +61,7 @@ namespace NTwain
         /// or
         /// setValueProvider
         /// </exception>
-        public CapWrapper(ICapControl source, CapabilityId capability,
+        public CapWrapper(IDataSource source, CapabilityId capability,
             Func<object, TValue> getConversionRoutine,
             Func<TValue, TWOneValue> setValueProvider)
         {
@@ -70,7 +73,8 @@ namespace NTwain
             _getConvertRoutine = getConversionRoutine;
             _setOneValueFunc = setValueProvider;
             Capability = capability;
-            SupportedActions = source.CapQuerySupport(capability);
+
+            CheckSupports();
         }
 
         /// <summary>
@@ -87,7 +91,7 @@ namespace NTwain
         /// or
         /// setValueRoutine
         /// </exception>
-        public CapWrapper(ICapControl source, CapabilityId capability,
+        public CapWrapper(IDataSource source, CapabilityId capability,
             Func<object, TValue> getConversionRoutine,
             Func<TValue, ReturnCode> setValueRoutine)
         {
@@ -99,7 +103,51 @@ namespace NTwain
             _getConvertRoutine = getConversionRoutine;
             _setCustomRoutine = setValueRoutine;
             Capability = capability;
-            SupportedActions = source.CapQuerySupport(capability);
+
+            CheckSupports();
+        }
+
+        private void CheckSupports()
+        {
+            if (!_supports.HasValue && _source.IsOpen)
+            {
+                var srcVersion = _source.ProtocolVersion;
+                if (srcVersion >= ProtocolVersions.GetMinimumVersion(Capability))
+                {
+                    _supports = _source.CapQuerySupport(Capability);
+
+                    if (!_supports.HasValue)
+                    {
+                        // lame source, have to guess using a get call
+                        using (TWCapability cap = new TWCapability(Capability))
+                        {
+                            var rc = _source.DGControl.Capability.Get(cap);
+                            if (rc == ReturnCode.Success)
+                            {
+                                // assume can do common things
+                                if (_readOnly)
+                                {
+                                    _supports = QuerySupports.Get | QuerySupports.GetCurrent | QuerySupports.GetDefault;
+                                }
+                                else
+                                {
+                                    _supports = QuerySupports.Get | QuerySupports.GetCurrent | QuerySupports.GetDefault |
+                                        QuerySupports.Set | QuerySupports.Reset | QuerySupports.SetConstraint;
+                                }
+
+                            }
+                            else
+                            {
+                                _supports = QuerySupports.None;
+                            }
+                        }
+                    }
+                }
+                else
+                {
+                    _supports = QuerySupports.None;
+                }
+            }
         }
 
 
@@ -118,13 +166,22 @@ namespace NTwain
         /// </value>
         public CapabilityId Capability { get; private set; }
 
+        QuerySupports? _supports;
+
         /// <summary>
         /// Gets the supported actions.
         /// </summary>
         /// <value>
         /// The supported actions.
         /// </value>
-        public QuerySupports SupportedActions { get; private set; }
+        public QuerySupports SupportedActions
+        {
+            get
+            {
+                CheckSupports();
+                return _supports.GetValueOrDefault();
+            }
+        }
 
         /// <summary>
         /// Gets a value indicating whether this capability is supported.
@@ -242,11 +299,7 @@ namespace NTwain
         /// <returns></returns>
         public IList<TValue> Get()
         {
-            if (CanGet)
-            {
-                return _source.CapGet(Capability).Select(o => _getConvertRoutine(o)).ToList();
-            }
-            return new List<TValue>();
+            return _source.CapGet(Capability).Select(o => _getConvertRoutine(o)).ToList();
         }
 
         /// <summary>
@@ -256,22 +309,20 @@ namespace NTwain
         public string GetLabel()
         {
             object value = null;
-            if (CanGetLabel)
-            {
-                using (TWCapability cap = new TWCapability(Capability))
-                {
-                    var rc = _source.DGControl.Capability.GetLabel(cap);
-                    if (rc == ReturnCode.Success)
-                    {
-                        var read = CapabilityReader.ReadValue(cap);
 
-                        switch (read.ContainerType)
-                        {
-                            case ContainerType.OneValue:
-                                // most likely not correct
-                                value = read.OneValue;
-                                break;
-                        }
+            using (TWCapability cap = new TWCapability(Capability))
+            {
+                var rc = _source.DGControl.Capability.GetLabel(cap);
+                if (rc == ReturnCode.Success)
+                {
+                    var read = CapabilityReader.ReadValue(cap);
+
+                    switch (read.ContainerType)
+                    {
+                        case ContainerType.OneValue:
+                            // most likely not correct
+                            value = read.OneValue;
+                            break;
                     }
                 }
             }
@@ -285,22 +336,19 @@ namespace NTwain
         public string GetHelp()
         {
             object value = null;
-            if (CanGetHelp)
+            using (TWCapability cap = new TWCapability(Capability))
             {
-                using (TWCapability cap = new TWCapability(Capability))
+                var rc = _source.DGControl.Capability.GetHelp(cap);
+                if (rc == ReturnCode.Success)
                 {
-                    var rc = _source.DGControl.Capability.GetHelp(cap);
-                    if (rc == ReturnCode.Success)
-                    {
-                        var read = CapabilityReader.ReadValue(cap);
+                    var read = CapabilityReader.ReadValue(cap);
 
-                        switch (read.ContainerType)
-                        {
-                            case ContainerType.OneValue:
-                                // most likely not correct
-                                value = read.OneValue;
-                                break;
-                        }
+                    switch (read.ContainerType)
+                    {
+                        case ContainerType.OneValue:
+                            // most likely not correct
+                            value = read.OneValue;
+                            break;
                     }
                 }
             }
@@ -314,15 +362,13 @@ namespace NTwain
         public IList<string> GetLabelEnum()
         {
             var list = new List<object>();
-            if (CanGetLabelEnum)
+
+            using (TWCapability cap = new TWCapability(Capability))
             {
-                using (TWCapability cap = new TWCapability(Capability))
+                var rc = _source.DGControl.Capability.GetLabelEnum(cap);
+                if (rc == ReturnCode.Success)
                 {
-                    var rc = _source.DGControl.Capability.GetLabelEnum(cap);
-                    if (rc == ReturnCode.Success)
-                    {
-                        CapabilityReader.ReadValue(cap).PopulateFromCapValues(list);
-                    }
+                    CapabilityReader.ReadValue(cap).PopulateFromCapValues(list);
                 }
             }
             return list.Select(o => o.ToString()).ToList();
@@ -350,24 +396,22 @@ namespace NTwain
         public ReturnCode Set(TValue value)
         {
             ReturnCode rc = ReturnCode.Failure;
-            if (CanSet)
+
+            if (_setCustomRoutine != null)
             {
-                if (_setCustomRoutine != null)
+                rc = _setCustomRoutine(value);
+            }
+            else if (_setOneValueFunc != null)
+            {
+                using (var cap = new TWCapability(Capability, _setOneValueFunc(value)))
                 {
-                    rc = _setCustomRoutine(value);
-                }
-                else if (_setOneValueFunc != null)
-                {
-                    using (var cap = new TWCapability(Capability, _setOneValueFunc(value)))
-                    {
-                        rc = _source.DGControl.Capability.Set(cap);
-                    }
-                }
-                else
-                {
-                    throw new InvalidOperationException("Simple Set() is not defined for this capability.");
+                    rc = _source.DGControl.Capability.Set(cap);
                 }
             }
+            else
+            {
+                throw new InvalidOperationException("Simple Set() is not defined for this capability.");
+            }
             return rc;
         }
 
@@ -379,12 +423,9 @@ namespace NTwain
         public ReturnCode Set(TWArray value)
         {
             ReturnCode rc = ReturnCode.Failure;
-            if (CanSet)
+            using (var cap = new TWCapability(Capability, value))
             {
-                using (var cap = new TWCapability(Capability, value))
-                {
-                    rc = _source.DGControl.Capability.Set(cap);
-                }
+                rc = _source.DGControl.Capability.Set(cap);
             }
             return rc;
         }
@@ -397,12 +438,9 @@ namespace NTwain
         public ReturnCode Set(TWEnumeration value)
         {
             ReturnCode rc = ReturnCode.Failure;
-            if (CanSet)
+            using (var cap = new TWCapability(Capability, value))
             {
-                using (var cap = new TWCapability(Capability, value))
-                {
-                    rc = _source.DGControl.Capability.Set(cap);
-                }
+                rc = _source.DGControl.Capability.Set(cap);
             }
             return rc;
         }
@@ -415,12 +453,9 @@ namespace NTwain
         public ReturnCode SetConstraint(TWOneValue value)
         {
             ReturnCode rc = ReturnCode.Failure;
-            if (CanSetConstraint)
+            using (var cap = new TWCapability(Capability, value))
             {
-                using (var cap = new TWCapability(Capability, value))
-                {
-                    rc = _source.DGControl.Capability.SetConstraint(cap);
-                }
+                rc = _source.DGControl.Capability.SetConstraint(cap);
             }
             return rc;
         }
@@ -433,12 +468,9 @@ namespace NTwain
         public ReturnCode SetConstraint(TWEnumeration value)
         {
             ReturnCode rc = ReturnCode.Failure;
-            if (CanSetConstraint)
+            using (var cap = new TWCapability(Capability, value))
             {
-                using (var cap = new TWCapability(Capability, value))
-                {
-                    rc = _source.DGControl.Capability.SetConstraint(cap);
-                }
+                rc = _source.DGControl.Capability.SetConstraint(cap);
             }
             return rc;
         }
@@ -451,12 +483,9 @@ namespace NTwain
         public ReturnCode SetConstraint(TWRange value)
         {
             ReturnCode rc = ReturnCode.Failure;
-            if (CanSetConstraint)
+            using (var cap = new TWCapability(Capability, value))
             {
-                using (var cap = new TWCapability(Capability, value))
-                {
-                    rc = _source.DGControl.Capability.SetConstraint(cap);
-                }
+                rc = _source.DGControl.Capability.SetConstraint(cap);
             }
             return rc;
         }
diff --git a/NTwain/DataSource.Caps.cs b/NTwain/DataSource.Caps.cs
index 0dc68ec..fe6d8c3 100644
--- a/NTwain/DataSource.Caps.cs
+++ b/NTwain/DataSource.Caps.cs
@@ -17,13 +17,13 @@ namespace NTwain
         #region low-level cap stuff
 
         /// <summary>
-        /// Gets the actual supported operations for a capability.
+        /// Gets the actual supported operations for a capability. This is not supported by all sources.
         /// </summary>
         /// <param name="capabilityId">The capability id.</param>
         /// <returns></returns>
-        public QuerySupports CapQuerySupport(CapabilityId capabilityId)
+        public QuerySupports? CapQuerySupport(CapabilityId capabilityId)
         {
-            QuerySupports retVal = QuerySupports.None;
+            QuerySupports? retVal = null;
             using (TWCapability cap = new TWCapability(capabilityId))
             {
                 var rc = _session.DGControl.Capability.QuerySupport(cap);
@@ -549,7 +549,7 @@ namespace NTwain
         {
             get
             {
-                return _physicalWidth ?? (_physicalWidth = new CapWrapper<TWFix32>(this, CapabilityId.ICapPhysicalWidth, ValueExtensions.ConvertToFix32));
+                return _physicalWidth ?? (_physicalWidth = new CapWrapper<TWFix32>(this, CapabilityId.ICapPhysicalWidth, ValueExtensions.ConvertToFix32, true));
             }
         }
 
@@ -565,7 +565,7 @@ namespace NTwain
         {
             get
             {
-                return _physicalHeight ?? (_physicalHeight = new CapWrapper<TWFix32>(this, CapabilityId.ICapPhysicalHeight, ValueExtensions.ConvertToFix32));
+                return _physicalHeight ?? (_physicalHeight = new CapWrapper<TWFix32>(this, CapabilityId.ICapPhysicalHeight, ValueExtensions.ConvertToFix32, true));
             }
         }
 
@@ -604,7 +604,7 @@ namespace NTwain
         {
             get
             {
-                return _nativeXRes ?? (_nativeXRes = new CapWrapper<TWFix32>(this, CapabilityId.ICapXNativeResolution, ValueExtensions.ConvertToFix32));
+                return _nativeXRes ?? (_nativeXRes = new CapWrapper<TWFix32>(this, CapabilityId.ICapXNativeResolution, ValueExtensions.ConvertToFix32, true));
             }
         }
 
@@ -620,7 +620,7 @@ namespace NTwain
         {
             get
             {
-                return _nativeYRes ?? (_nativeYRes = new CapWrapper<TWFix32>(this, CapabilityId.ICapYNativeResolution, ValueExtensions.ConvertToFix32));
+                return _nativeYRes ?? (_nativeYRes = new CapWrapper<TWFix32>(this, CapabilityId.ICapYNativeResolution, ValueExtensions.ConvertToFix32, true));
             }
         }
 
@@ -1101,7 +1101,7 @@ namespace NTwain
         {
             get
             {
-                return _minHeight ?? (_minHeight = new CapWrapper<TWFix32>(this, CapabilityId.ICapMinimumHeight, ValueExtensions.ConvertToFix32));
+                return _minHeight ?? (_minHeight = new CapWrapper<TWFix32>(this, CapabilityId.ICapMinimumHeight, ValueExtensions.ConvertToFix32, true));
             }
         }
 
@@ -1117,7 +1117,7 @@ namespace NTwain
         {
             get
             {
-                return _minWidth ?? (_minWidth = new CapWrapper<TWFix32>(this, CapabilityId.ICapMinimumWidth, ValueExtensions.ConvertToFix32));
+                return _minWidth ?? (_minWidth = new CapWrapper<TWFix32>(this, CapabilityId.ICapMinimumWidth, ValueExtensions.ConvertToFix32, true));
             }
         }
 
@@ -1196,7 +1196,7 @@ namespace NTwain
         {
             get
             {
-                return _barcodeType ?? (_barcodeType = new CapWrapper<BarcodeType>(this, CapabilityId.ICapSupportedBarcodeTypes, ValueExtensions.ConvertToEnum<BarcodeType>));
+                return _barcodeType ?? (_barcodeType = new CapWrapper<BarcodeType>(this, CapabilityId.ICapSupportedBarcodeTypes, ValueExtensions.ConvertToEnum<BarcodeType>, true));
             }
         }
 
@@ -1359,7 +1359,7 @@ namespace NTwain
         {
             get
             {
-                return _patchcodeType ?? (_patchcodeType = new CapWrapper<PatchCode>(this, CapabilityId.ICapSupportedPatchCodeTypes, ValueExtensions.ConvertToEnum<PatchCode>));
+                return _patchcodeType ?? (_patchcodeType = new CapWrapper<PatchCode>(this, CapabilityId.ICapSupportedPatchCodeTypes, ValueExtensions.ConvertToEnum<PatchCode>, true));
             }
         }
 
@@ -1726,7 +1726,7 @@ namespace NTwain
         {
             get
             {
-                return _cropUseFrame ?? (_cropUseFrame = new CapWrapper<BoolType>(this, CapabilityId.ICapAutomaticCropUsesFrame, ValueExtensions.ConvertToEnum<BoolType>));
+                return _cropUseFrame ?? (_cropUseFrame = new CapWrapper<BoolType>(this, CapabilityId.ICapAutomaticCropUsesFrame, ValueExtensions.ConvertToEnum<BoolType>, true));
             }
         }
 
@@ -1868,7 +1868,7 @@ namespace NTwain
         {
             get
             {
-                return _supportedExtInfo ?? (_supportedExtInfo = new CapWrapper<ExtendedImageInfo>(this, CapabilityId.ICapSupportedExtImageInfo, ValueExtensions.ConvertToEnum<ExtendedImageInfo>));
+                return _supportedExtInfo ?? (_supportedExtInfo = new CapWrapper<ExtendedImageInfo>(this, CapabilityId.ICapSupportedExtImageInfo, ValueExtensions.ConvertToEnum<ExtendedImageInfo>, true));
             }
         }
 
@@ -2026,7 +2026,7 @@ namespace NTwain
         {
             get
             {
-                return _feederLoaded ?? (_feederLoaded = new CapWrapper<BoolType>(this, CapabilityId.CapFeederLoaded, ValueExtensions.ConvertToEnum<BoolType>));
+                return _feederLoaded ?? (_feederLoaded = new CapWrapper<BoolType>(this, CapabilityId.CapFeederLoaded, ValueExtensions.ConvertToEnum<BoolType>, true));
             }
         }
 
@@ -2035,7 +2035,7 @@ namespace NTwain
         private CapWrapper<CapabilityId> _supportedCaps;
 
         /// <summary>
-        /// Gets the supported caps for the current source.
+        /// Gets the supported caps for the current source. This is not supported by all sources.
         /// </summary>
         /// <value>
         /// The supported caps.
@@ -2044,7 +2044,7 @@ namespace NTwain
         {
             get
             {
-                return _supportedCaps ?? (_supportedCaps = new CapWrapper<CapabilityId>(this, CapabilityId.CapSupportedCaps, value => value.ConvertToEnum<CapabilityId>(false)));
+                return _supportedCaps ?? (_supportedCaps = new CapWrapper<CapabilityId>(this, CapabilityId.CapSupportedCaps, value => value.ConvertToEnum<CapabilityId>(false), true));
             }
         }
 
@@ -2186,7 +2186,7 @@ namespace NTwain
         {
             get
             {
-                return _paperDetectable ?? (_paperDetectable = new CapWrapper<BoolType>(this, CapabilityId.CapPaperDetectable, ValueExtensions.ConvertToEnum<BoolType>));
+                return _paperDetectable ?? (_paperDetectable = new CapWrapper<BoolType>(this, CapabilityId.CapPaperDetectable, ValueExtensions.ConvertToEnum<BoolType>, true));
             }
         }
 
@@ -2202,7 +2202,7 @@ namespace NTwain
         {
             get
             {
-                return _uiControllable ?? (_uiControllable = new CapWrapper<BoolType>(this, CapabilityId.CapUIControllable, ValueExtensions.ConvertToEnum<BoolType>));
+                return _uiControllable ?? (_uiControllable = new CapWrapper<BoolType>(this, CapabilityId.CapUIControllable, ValueExtensions.ConvertToEnum<BoolType>, true));
             }
         }
 
@@ -2218,7 +2218,7 @@ namespace NTwain
         {
             get
             {
-                return _devOnline ?? (_devOnline = new CapWrapper<BoolType>(this, CapabilityId.CapDeviceOnline, ValueExtensions.ConvertToEnum<BoolType>));
+                return _devOnline ?? (_devOnline = new CapWrapper<BoolType>(this, CapabilityId.CapDeviceOnline, ValueExtensions.ConvertToEnum<BoolType>, true));
             }
         }
 
@@ -2276,7 +2276,7 @@ namespace NTwain
         {
             get
             {
-                return _duplex ?? (_duplex = new CapWrapper<Duplex>(this, CapabilityId.CapDuplex, ValueExtensions.ConvertToEnum<Duplex>));
+                return _duplex ?? (_duplex = new CapWrapper<Duplex>(this, CapabilityId.CapDuplex, ValueExtensions.ConvertToEnum<Duplex>, true));
             }
         }
 
@@ -2313,7 +2313,7 @@ namespace NTwain
         {
             get
             {
-                return _dsUIonly ?? (_dsUIonly = new CapWrapper<BoolType>(this, CapabilityId.CapEnableDSUIOnly, ValueExtensions.ConvertToEnum<BoolType>));
+                return _dsUIonly ?? (_dsUIonly = new CapWrapper<BoolType>(this, CapabilityId.CapEnableDSUIOnly, ValueExtensions.ConvertToEnum<BoolType>, true));
             }
         }
 
@@ -2329,7 +2329,7 @@ namespace NTwain
         {
             get
             {
-                return _dsData ?? (_dsData = new CapWrapper<BoolType>(this, CapabilityId.CapCustomDSData, ValueExtensions.ConvertToEnum<BoolType>));
+                return _dsData ?? (_dsData = new CapWrapper<BoolType>(this, CapabilityId.CapCustomDSData, ValueExtensions.ConvertToEnum<BoolType>, true));
             }
         }
 
@@ -2536,7 +2536,7 @@ namespace NTwain
         {
             get
             {
-                return _powerSup ?? (_powerSup = new CapWrapper<PowerSupply>(this, CapabilityId.CapPowerSupply, ValueExtensions.ConvertToEnum<PowerSupply>));
+                return _powerSup ?? (_powerSup = new CapWrapper<PowerSupply>(this, CapabilityId.CapPowerSupply, ValueExtensions.ConvertToEnum<PowerSupply>, true));
             }
         }
 
@@ -2552,7 +2552,7 @@ namespace NTwain
         {
             get
             {
-                return _camPreviewUI ?? (_camPreviewUI = new CapWrapper<BoolType>(this, CapabilityId.CapCameraPreviewUI, ValueExtensions.ConvertToEnum<BoolType>));
+                return _camPreviewUI ?? (_camPreviewUI = new CapWrapper<BoolType>(this, CapabilityId.CapCameraPreviewUI, ValueExtensions.ConvertToEnum<BoolType>, true));
             }
         }
 
@@ -2589,7 +2589,7 @@ namespace NTwain
         {
             get
             {
-                return _serialNo ?? (_serialNo = new CapWrapper<string>(this, CapabilityId.CapSerialNumber, value => { return value.ToString(); }));
+                return _serialNo ?? (_serialNo = new CapWrapper<string>(this, CapabilityId.CapSerialNumber, value => { return value.ToString(); }, true));
             }
         }
 
@@ -2754,7 +2754,7 @@ namespace NTwain
         {
             get
             {
-                return _reacuireAllow ?? (_reacuireAllow = new CapWrapper<BoolType>(this, CapabilityId.CapReacquireAllowed, ValueExtensions.ConvertToEnum<BoolType>));
+                return _reacuireAllow ?? (_reacuireAllow = new CapWrapper<BoolType>(this, CapabilityId.CapReacquireAllowed, ValueExtensions.ConvertToEnum<BoolType>, true));
             }
         }
 
@@ -2770,7 +2770,7 @@ namespace NTwain
         {
             get
             {
-                return _battMinutes ?? (_battMinutes = new CapWrapper<int>(this, CapabilityId.CapBatteryMinutes, ValueExtensions.ConvertToEnum<int>));
+                return _battMinutes ?? (_battMinutes = new CapWrapper<int>(this, CapabilityId.CapBatteryMinutes, ValueExtensions.ConvertToEnum<int>, true));
             }
         }
 
@@ -2786,7 +2786,7 @@ namespace NTwain
         {
             get
             {
-                return _battPercent ?? (_battPercent = new CapWrapper<int>(this, CapabilityId.CapBatteryPercentage, ValueExtensions.ConvertToEnum<int>));
+                return _battPercent ?? (_battPercent = new CapWrapper<int>(this, CapabilityId.CapBatteryPercentage, ValueExtensions.ConvertToEnum<int>, true));
             }
         }
 
@@ -2970,7 +2970,7 @@ namespace NTwain
         {
             get
             {
-                return _custGuid ?? (_custGuid = new CapWrapper<string>(this, CapabilityId.CapCustomInterfaceGuid, value => { return value.ToString(); }));
+                return _custGuid ?? (_custGuid = new CapWrapper<string>(this, CapabilityId.CapCustomInterfaceGuid, value => { return value.ToString(); }, true));
             }
         }
 
@@ -2986,7 +2986,7 @@ namespace NTwain
         {
             get
             {
-                return _supportedCapsUnique ?? (_supportedCapsUnique = new CapWrapper<CapabilityId>(this, CapabilityId.CapSupportedCapsSegmentUnique, value => value.ConvertToEnum<CapabilityId>(false)));
+                return _supportedCapsUnique ?? (_supportedCapsUnique = new CapWrapper<CapabilityId>(this, CapabilityId.CapSupportedCapsSegmentUnique, value => value.ConvertToEnum<CapabilityId>(false), true));
             }
         }
 
@@ -3002,7 +3002,7 @@ namespace NTwain
         {
             get
             {
-                return _supportedDat ?? (_supportedDat = new CapWrapper<uint>(this, CapabilityId.CapSupportedDATs, ValueExtensions.ConvertToEnum<uint>));
+                return _supportedDat ?? (_supportedDat = new CapWrapper<uint>(this, CapabilityId.CapSupportedDATs, ValueExtensions.ConvertToEnum<uint>, true));
             }
         }
 
@@ -3207,7 +3207,7 @@ namespace NTwain
         {
             get
             {
-                return _printFontStyle ?? (_printFontStyle = new CapWrapper<PrinterFontStyle>(this, CapabilityId.CapPrinterFontStyle, ValueExtensions.ConvertToEnum<PrinterFontStyle>));
+                return _printFontStyle ?? (_printFontStyle = new CapWrapper<PrinterFontStyle>(this, CapabilityId.CapPrinterFontStyle, ValueExtensions.ConvertToEnum<PrinterFontStyle>, false));
             }
         }
 
@@ -3288,7 +3288,7 @@ namespace NTwain
         {
             get
             {
-                return _printIdxTrig ?? (_printIdxTrig = new CapWrapper<PrinterIndexTrigger>(this, CapabilityId.CapPrinterIndexTrigger, ValueExtensions.ConvertToEnum<PrinterIndexTrigger>));
+                return _printIdxTrig ?? (_printIdxTrig = new CapWrapper<PrinterIndexTrigger>(this, CapabilityId.CapPrinterIndexTrigger, ValueExtensions.ConvertToEnum<PrinterIndexTrigger>, false));
             }
         }
 
@@ -3304,7 +3304,7 @@ namespace NTwain
         {
             get
             {
-                return _printPreview ?? (_printPreview = new CapWrapper<string>(this, CapabilityId.CapPrinterStringPreview, value => { return value.ToString(); }));
+                return _printPreview ?? (_printPreview = new CapWrapper<string>(this, CapabilityId.CapPrinterStringPreview, value => { return value.ToString(); }, true));
             }
         }
 
diff --git a/NTwain/DataSource.cs b/NTwain/DataSource.cs
index 9355a2e..716393a 100644
--- a/NTwain/DataSource.cs
+++ b/NTwain/DataSource.cs
@@ -150,22 +150,31 @@ namespace NTwain
         /// </value>
         public Version ProtocolVersion { get; private set; }
 
+        /// <summary>
+        /// Gets a value indicating whether this data source has been opened.
+        /// </summary>
+        /// <value>
+        ///   <c>true</c> if this data source is open; otherwise, <c>false</c>.
+        /// </value>
+        public bool IsOpen { get { return _session.IsSourceOpen; } }
+
         static readonly CapabilityId[] _emptyCapList = new CapabilityId[0];
 
         private IList<CapabilityId> _supportedCapsList;
         /// <summary>
-        /// Gets the list of supported caps for this source.
+        /// Gets the list of supported caps for this source. 
         /// </summary>
         /// <value>
         /// The supported caps.
         /// </value>
+        [Obsolete("Use CapSupportedCaps.Get() instead.")]
         public IList<CapabilityId> SupportedCaps
         {
             get
             {
                 if (_supportedCapsList == null && _session.State > 3)
                 {
-                    _supportedCapsList = CapSupportedCaps.Get();// CapGet(CapabilityId.CapSupportedCaps).CastToEnum<CapabilityId>(false);
+                    _supportedCapsList = CapSupportedCaps.Get();
                 }
                 return _supportedCapsList ?? _emptyCapList;
             }
diff --git a/NTwain/DataTransferredEventArgs.cs b/NTwain/DataTransferredEventArgs.cs
index 383c02b..cb61889 100644
--- a/NTwain/DataTransferredEventArgs.cs
+++ b/NTwain/DataTransferredEventArgs.cs
@@ -111,7 +111,7 @@ namespace NTwain
         /// <exception cref="System.InvalidOperationException"></exception>
         public IEnumerable<TWInfo> GetExtImageInfo(params ExtendedImageInfo[] infoIds)
         {
-            if (infoIds != null && infoIds.Length > 0 && DataSource.SupportedCaps.Contains(CapabilityId.ICapExtImageInfo))
+            if (infoIds != null && infoIds.Length > 0)// && DataSource.SupportedCaps.Contains(CapabilityId.ICapExtImageInfo))
             {
                 var request = new TWExtImageInfo { NumInfos = (uint)infoIds.Length };
                 if (infoIds.Length > request.Info.Length)
diff --git a/NTwain/ICapControl.cs b/NTwain/ICapControl.cs
index 105ebba..c74a42b 100644
--- a/NTwain/ICapControl.cs
+++ b/NTwain/ICapControl.cs
@@ -35,7 +35,7 @@ namespace NTwain
         /// </summary>
         /// <param name="capabilityId">The capability identifier.</param>
         /// <returns></returns>
-        QuerySupports CapQuerySupport(CapabilityId capabilityId);
+        QuerySupports? CapQuerySupport(CapabilityId capabilityId);
 
         /// <summary>
         /// Resets the current value to power-on default.
diff --git a/NTwain/ICapWrapper.cs b/NTwain/ICapWrapper.cs
index fc712fd..26c041d 100644
--- a/NTwain/ICapWrapper.cs
+++ b/NTwain/ICapWrapper.cs
@@ -128,20 +128,12 @@ namespace NTwain
         IList<string> GetLabelEnum();
 
         /// <summary>
-        /// Gets a value indicating whether this capability is supported.
+        /// Gets a value indicating whether this capability is at all supported.
         /// </summary>
         /// <value>
         /// <c>true</c> if this capability is supported; otherwise, <c>false</c>.
         /// </value>
         bool IsSupported { get; }
-
-        /// <summary>
-        /// Gets the supported actions.
-        /// </summary>
-        /// <value>
-        /// The supported actions.
-        /// </value>
-        QuerySupports SupportedActions { get; }
     }
 
     /// <summary>
diff --git a/NTwain/IDataSource.cs b/NTwain/IDataSource.cs
index a3f9875..34b8f8b 100644
--- a/NTwain/IDataSource.cs
+++ b/NTwain/IDataSource.cs
@@ -6,7 +6,7 @@ namespace NTwain
     /// <summary>
     /// Represents a TWAIN data source.
     /// </summary>
-    public interface IDataSource
+    public interface IDataSource : ICapControl
     {
         /// <summary>
         /// Gets the source's product name.
@@ -64,6 +64,14 @@ namespace NTwain
         /// </value>
         TWVersion Version { get; }
 
+        /// <summary>
+        /// Gets a value indicating whether this data source has been opened.
+        /// </summary>
+        /// <value>
+        ///   <c>true</c> if this data source is open; otherwise, <c>false</c>.
+        /// </value>
+        bool IsOpen { get; }
+
         /// <summary>
         /// Opens the source for capability negotiation.
         /// </summary>
diff --git a/NTwain/NTwain.csproj b/NTwain/NTwain.csproj
index b3e67f6..e94e8c9 100644
--- a/NTwain/NTwain.csproj
+++ b/NTwain/NTwain.csproj
@@ -88,6 +88,7 @@
     </Compile>
     <Compile Include="Properties\VersionInfo.cs" />
     <Compile Include="Internals\TentativeStateCommitable.cs" />
+    <Compile Include="ProtocolVersions.cs" />
     <Compile Include="State.cs" />
     <Compile Include="TransferErrorEventArgs.cs" />
     <Compile Include="TransferReadyEventArgs.cs" />
diff --git a/NTwain/Properties/VersionInfo.cs b/NTwain/Properties/VersionInfo.cs
index 9c94307..02d78e9 100644
--- a/NTwain/Properties/VersionInfo.cs
+++ b/NTwain/Properties/VersionInfo.cs
@@ -23,7 +23,7 @@ namespace NTwain
         /// <summary>
         /// The build release version number.
         /// </summary>
-        public const string Build = "3.2.6"; // change this for each nuget release
+        public const string Build = "3.2.7"; // change this for each nuget release
 
 
     }
diff --git a/NTwain/ProtocolVersions.cs b/NTwain/ProtocolVersions.cs
new file mode 100644
index 0000000..d39a137
--- /dev/null
+++ b/NTwain/ProtocolVersions.cs
@@ -0,0 +1,209 @@
+using NTwain.Data;
+using System;
+using System.Collections.Generic;
+
+namespace NTwain
+{
+    /// <summary>
+    /// Contains the minimum TWAIN protocol version for various things.
+    /// </summary>
+    public static class ProtocolVersions
+    {
+        internal static readonly Version v10 = new Version(1, 0);
+        internal static readonly Version v11 = new Version(1, 1);
+        internal static readonly Version v15 = new Version(1, 5);
+        internal static readonly Version v16 = new Version(1, 6);
+        internal static readonly Version v17 = new Version(1, 7);
+        internal static readonly Version v18 = new Version(1, 8);
+        internal static readonly Version v19 = new Version(1, 9);
+        internal static readonly Version v20 = new Version(2, 0);
+        internal static readonly Version v21 = new Version(2, 1);
+        internal static readonly Version v22 = new Version(2, 2);
+        internal static readonly Version v23 = new Version(2, 3);
+
+
+        static readonly Dictionary<CapabilityId, Version> __capMinVersions = new Dictionary<CapabilityId, Version>
+        {
+            { CapabilityId.ACapXferMech, v18 },
+
+            { CapabilityId.CapAlarms, v18 },
+            { CapabilityId.CapAlarmVolume, v18 },
+            { CapabilityId.CapAuthor, v10 },
+            { CapabilityId.CapAutoFeed, v10 },
+            { CapabilityId.CapAutomaticCapture, v18 },
+            { CapabilityId.CapAutomaticSenseMedium, v21 },
+            { CapabilityId.CapAutoScan, v16 },
+            { CapabilityId.CapBatteryMinutes, v18 },
+            { CapabilityId.CapBatteryPercentage, v18 },
+            { CapabilityId.CapCameraEnabled, v20 },
+            { CapabilityId.CapCameraOrder, v20 },
+            { CapabilityId.CapCameraPreviewUI, v18 },
+            { CapabilityId.CapCameraSide, v19 },
+            { CapabilityId.CapCaption, v10 },
+            { CapabilityId.CapClearBuffers, v18 },
+            { CapabilityId.CapClearPage, v10 },
+            { CapabilityId.CapCustomDSData, v17 },
+            { CapabilityId.CapCustomInterfaceGuid, v21 },
+            { CapabilityId.CapDeviceEvent, v18 },
+            { CapabilityId.CapDeviceOnline, v16 },
+            { CapabilityId.CapDeviceTimeDate, v18 },
+            { CapabilityId.CapDoubleFeedDetection, v22 },
+            { CapabilityId.CapDoubleFeedDetectionLength, v22 },
+            { CapabilityId.CapDoubleFeedDetectionResponse, v22 },
+            { CapabilityId.CapDoubleFeedDetectionSensitivity, v22 },
+            { CapabilityId.CapDuplex, v17 },
+            { CapabilityId.CapDuplexEnabled, v17 },
+            { CapabilityId.CapEnableDSUIOnly, v17 },
+            { CapabilityId.CapEndorser, v17 },
+            { CapabilityId.CapExtendedCaps, v10 },
+            { CapabilityId.CapFeederAlignment, v18 },
+            { CapabilityId.CapFeederEnabled, v10 },
+            { CapabilityId.CapFeederLoaded, v10 },
+            { CapabilityId.CapFeederOrder, v18 },
+            { CapabilityId.CapFeederPocket, v20 },
+            { CapabilityId.CapFeederPrep, v20},
+            { CapabilityId.CapFeedPage, v10 },
+            { CapabilityId.CapIndicators, v11 },
+            { CapabilityId.CapIndicatorsMode, v22 },
+            { CapabilityId.CapJobControl, v17 },
+            { CapabilityId.CapLanguage, v18 },
+            { CapabilityId.CapMaxBatchBuffers, v18 },
+            { CapabilityId.CapMicrEnabled, v20 },
+            { CapabilityId.CapPaperDetectable, v16 },
+            { CapabilityId.CapPaperHandling, v22 },
+            { CapabilityId.CapPowerSaveTime, v18 },
+            { CapabilityId.CapPowerSupply, v18 },
+            { CapabilityId.CapPrinter, v18 },
+            { CapabilityId.CapPrinterEnabled, v18 },
+            { CapabilityId.CapPrinterCharRotation, v23 },
+            { CapabilityId.CapPrinterFontStyle, v23 },
+            { CapabilityId.CapPrinterIndex, v18 },
+            { CapabilityId.CapPrinterIndexLeadChar, v23 },
+            { CapabilityId.CapPrinterIndexMaxValue, v23 },
+            { CapabilityId.CapPrinterIndexNumDigits, v23 },
+            { CapabilityId.CapPrinterIndexStep, v23 },
+            { CapabilityId.CapPrinterIndexTrigger, v23 },
+            { CapabilityId.CapPrinterMode, v18 },
+            { CapabilityId.CapPrinterString, v18 },
+            { CapabilityId.CapPrinterStringPreview, v23 },
+            { CapabilityId.CapPrinterSuffix, v18 },
+            { CapabilityId.CapPrinterVerticalOffset, v22 },
+            { CapabilityId.CapReacquireAllowed, v18 },
+            { CapabilityId.CapRewindPage, v10 },
+            { CapabilityId.CapSegmented, v19 },
+            { CapabilityId.CapSerialNumber, v18 },
+            { CapabilityId.CapSupportedCaps, v10 },
+            { CapabilityId.CapSupportedCapsSegmentUnique, v22 },
+            { CapabilityId.CapSupportedDATs, v22 },
+            { CapabilityId.CapTimeBeforeFirstCapture, v18 },
+            { CapabilityId.CapTimeBetweenCaptures, v18 },
+            { CapabilityId.CapTimeDate, v10 },
+            { CapabilityId.CapThumbnailsEnabled, v17 },
+            { CapabilityId.CapUIControllable, v16 },
+            { CapabilityId.CapXferCount, v10 },
+
+            { CapabilityId.ICapAutoBright, v10 },
+            { CapabilityId.ICapAutoDiscardBlankPages, v20 },
+            { CapabilityId.ICapAutomaticBorderDetection, v18 },
+            { CapabilityId.ICapAutomaticColorEnabled, v21 },
+            { CapabilityId.ICapAutomaticColorNonColorPixelType, v18 },
+            { CapabilityId.ICapAutomaticCropUsesFrame, v21 },
+            { CapabilityId.ICapAutomaticDeskew, v18 },
+            { CapabilityId.ICapAutomaticLengthDetection, v21 },
+            { CapabilityId.ICapAutomaticRotate, v18 },
+            { CapabilityId.ICapAutoSize, v20 },
+            { CapabilityId.ICapBarcodeDetectionEnabled, v18 },
+            { CapabilityId.ICapBarcodeMaxRetries, v18 },
+            { CapabilityId.ICapBarcodeMaxSearchPriorities, v18 },
+            { CapabilityId.ICapBarcodeSearchMode, v18 },
+            { CapabilityId.ICapBarcodeSearchPriorities, v18 },
+            { CapabilityId.ICapBarcodeTimeout, v18 },
+            { CapabilityId.ICapBitDepth, v10 },
+            { CapabilityId.ICapBitDepthReduction, v15 },
+            { CapabilityId.ICapBitOrder, v10 },
+            { CapabilityId.ICapBitOrderCodes, v10 },
+            { CapabilityId.ICapBrightness, v10 },
+            { CapabilityId.ICapCCITTKFactor, v10 },
+            { CapabilityId.ICapColorManagementEnabled, v21 },
+            { CapabilityId.ICapCompression, v10 },
+            { CapabilityId.ICapContrast, v10 },
+            { CapabilityId.ICapCustHalftone, v10 },
+            { CapabilityId.ICapExposureTime, v10 },
+            { CapabilityId.ICapExtImageInfo, v17 },
+            { CapabilityId.ICapFeederType, v19 },
+            { CapabilityId.ICapFilmType, v22 },
+            { CapabilityId.ICapFilter, v10 },
+            { CapabilityId.ICapFlashUsed, v16 }, // maybe
+            { CapabilityId.ICapFlashUsed2, v18 },
+            { CapabilityId.ICapFlipRotation, v18 },
+            { CapabilityId.ICapFrames, v10 },
+            { CapabilityId.ICapGamma, v10 },
+            { CapabilityId.ICapHalftones, v10 },
+            { CapabilityId.ICapHighlight, v10 },
+            { CapabilityId.ICapICCProfile, v19 },
+            { CapabilityId.ICapImageDataSet, v17 },
+            { CapabilityId.ICapImageFileFormat, v10 },
+            { CapabilityId.ICapImageFilter, v18 },
+            { CapabilityId.ICapImageMerge, v21 },
+            { CapabilityId.ICapImageMergeHeightThreshold, v21 },
+            { CapabilityId.ICapJpegPixelType, v10 },
+            { CapabilityId.ICapJpegQuality, v19 },
+            { CapabilityId.ICapJpegSubsampling, v22 },
+            { CapabilityId.ICapLampState, v10 },
+            { CapabilityId.ICapLightPath, v10 },
+            { CapabilityId.ICapLightSource, v10 },
+            { CapabilityId.ICapMaxFrames, v10 },
+            { CapabilityId.ICapMinimumHeight, v17 },
+            { CapabilityId.ICapMinimumWidth, v17 },
+            { CapabilityId.ICapMirror, v22 },
+            { CapabilityId.ICapNoiseFilter, v18 },
+            { CapabilityId.ICapOrientation, v10 },
+            { CapabilityId.ICapOverScan, v18 },
+            { CapabilityId.ICapPatchCodeDetectionEnabled, v18 },
+            { CapabilityId.ICapPatchCodeMaxRetries, v18 },
+            { CapabilityId.ICapPatchCodeMaxSearchPriorities, v18 },
+            { CapabilityId.ICapPatchCodeSearchMode, v18 },
+            { CapabilityId.ICapPatchCodeSearchPriorities, v18 },
+            { CapabilityId.ICapPatchCodeTimeout, v18 },
+            { CapabilityId.ICapPhysicalHeight, v10 },
+            { CapabilityId.ICapPhysicalWidth, v10 },
+            { CapabilityId.ICapPixelFlavor, v10 },
+            { CapabilityId.ICapPixelFlavorCodes, v10 },
+            { CapabilityId.ICapPixelType, v10 },
+            { CapabilityId.ICapPlanarChunky, v10 },
+            { CapabilityId.ICapRotation, v10 },
+            { CapabilityId.ICapShadow, v10 },
+            { CapabilityId.ICapSupportedBarcodeTypes, v18 },
+            { CapabilityId.ICapSupportedExtImageInfo, v21 },
+            { CapabilityId.ICapSupportedPatchCodeTypes, v18 },
+            { CapabilityId.ICapSupportedSizes, v10 },
+            { CapabilityId.ICapThreshold, v10 },
+            { CapabilityId.ICapTiles, v10 },
+            { CapabilityId.ICapTimeFill, v10 },
+            { CapabilityId.ICapUndefinedImageSize, v16 },
+            { CapabilityId.ICapUnits, v10 },
+            { CapabilityId.ICapXferMech, v10 },
+            { CapabilityId.ICapXNativeResolution, v10 },
+            { CapabilityId.ICapXResolution, v10 },
+            { CapabilityId.ICapXScaling, v10 },
+            { CapabilityId.ICapYNativeResolution, v10 },
+            { CapabilityId.ICapYResolution, v10 },
+            { CapabilityId.ICapYScaling, v10 },
+            { CapabilityId.ICapZoomFactor, v18 },
+        };
+
+        /// <summary>
+        /// Gets the minimum TWAIN protocol version for a capability.
+        /// </summary>
+        /// <param name="id">The capability type.</param>
+        /// <returns></returns>
+        public static Version GetMinimumVersion(CapabilityId id)
+        {
+            if (__capMinVersions.ContainsKey(id))
+            {
+                return __capMinVersions[id];
+            }
+            return v10;
+        }
+    }
+}
diff --git a/Tests/Tester.WPF/Tester.WPF.csproj b/Tests/Tester.WPF/Tester.WPF.csproj
index f745f83..fb7d17d 100644
--- a/Tests/Tester.WPF/Tester.WPF.csproj
+++ b/Tests/Tester.WPF/Tester.WPF.csproj
@@ -70,7 +70,7 @@
     </Reference>
     <Reference Include="ModernWPF, Version=1.0.0.0, Culture=neutral, PublicKeyToken=c99d0cfbea7491ef, processorArchitecture=MSIL">
       <SpecificVersion>False</SpecificVersion>
-      <HintPath>..\..\packages\ModernWPF.1.2.9.1\lib\net40-Client\ModernWPF.dll</HintPath>
+      <HintPath>..\..\packages\ModernWPF.1.2.9.4\lib\net40-Client\ModernWPF.dll</HintPath>
     </Reference>
     <Reference Include="ModernWPF.Mvvm">
       <HintPath>..\..\packages\ModernWPF.Mvvm.0.7.0\lib\net40-Client\ModernWPF.Mvvm.dll</HintPath>
diff --git a/Tests/Tester.WPF/ViewModels/CapVM.cs b/Tests/Tester.WPF/ViewModels/CapVM.cs
index 76f2095..8d10470 100644
--- a/Tests/Tester.WPF/ViewModels/CapVM.cs
+++ b/Tests/Tester.WPF/ViewModels/CapVM.cs
@@ -21,7 +21,7 @@ namespace Tester.WPF
         {
             _ds = ds;
             Cap = cap;
-            Supports = ds.CapQuerySupport(cap);
+
 
             var capName = cap.ToString();
             var wrapProperty = ds.GetType().GetProperty(capName);
@@ -33,6 +33,22 @@ namespace Tester.WPF
                 _getCurrentMethod = wrapperType.GetMethod("GetCurrent");
                 _setMethod = wrapperType.GetMethods().FirstOrDefault(m => m.Name == "Set");
             }
+
+            var supportTest = ds.CapQuerySupport(cap);
+            if (supportTest.HasValue)
+            {
+                Supports = supportTest.Value;
+            }
+            else
+            {
+                if (_wrapper != null)
+                {
+                    var wrapperType = _wrapper.GetType();
+                    QuerySupports? supports = (QuerySupports?)wrapperType.GetProperty("SupportedActions").GetGetMethod().Invoke(_wrapper, null);
+                    Supports = supports.GetValueOrDefault();
+                }
+            }
+
         }
 
         public IEnumerable Get()
diff --git a/Tests/Tester.WPF/ViewModels/DataSourceVM.cs b/Tests/Tester.WPF/ViewModels/DataSourceVM.cs
index 0f75562..90a2579 100644
--- a/Tests/Tester.WPF/ViewModels/DataSourceVM.cs
+++ b/Tests/Tester.WPF/ViewModels/DataSourceVM.cs
@@ -49,7 +49,7 @@ namespace Tester.WPF
             //rc = DGControl.Status.Get(dsId, ref stat);
             if (rc == ReturnCode.Success)
             {
-                foreach (var c in DS.SupportedCaps.Select(o => new CapVM(DS, o)))
+                foreach (var c in DS.CapSupportedCaps.Get().Select(o => new CapVM(DS, o)))
                 {
                     Caps.Add(c);
                 }
diff --git a/Tests/Tester.WPF/ViewModels/TwainVM.cs b/Tests/Tester.WPF/ViewModels/TwainVM.cs
index ee90526..26675b5 100644
--- a/Tests/Tester.WPF/ViewModels/TwainVM.cs
+++ b/Tests/Tester.WPF/ViewModels/TwainVM.cs
@@ -35,6 +35,7 @@ namespace Tester.WPF
             _session.TransferReady += _session_TransferReady;
             _session.DataTransferred += _session_DataTransferred;
             _session.SourceDisabled += _session_SourceDisabled;
+            _session.StateChanged += (s, e) => { RaisePropertyChanged(() => State); };
         }
 
         TwainSession _session;
diff --git a/Tests/Tester.WPF/packages.config b/Tests/Tester.WPF/packages.config
index b52fe3a..249fd39 100644
--- a/Tests/Tester.WPF/packages.config
+++ b/Tests/Tester.WPF/packages.config
@@ -4,7 +4,7 @@
   <package id="CommonWin32" version="2.0.5.5" targetFramework="net40-Client" />
   <package id="Microsoft.WindowsAPICodePack-Core" version="1.1.0.0" targetFramework="net40-Client" />
   <package id="Microsoft.WindowsAPICodePack-Shell" version="1.1.0.0" targetFramework="net40-Client" />
-  <package id="ModernWPF" version="1.2.9.1" targetFramework="net40-Client" />
+  <package id="ModernWPF" version="1.2.9.4" targetFramework="net40-Client" />
   <package id="ModernWPF.Mvvm" version="0.7.0" targetFramework="net40-Client" />
   <package id="MvvmLightLibs" version="5.0.2.0" targetFramework="net40-Client" />
 </packages>
\ No newline at end of file
diff --git a/Tests/Tester.Winform/TestForm.cs b/Tests/Tester.Winform/TestForm.cs
index 4ca48ff..767aea2 100644
--- a/Tests/Tester.Winform/TestForm.cs
+++ b/Tests/Tester.Winform/TestForm.cs
@@ -70,6 +70,10 @@ namespace Tester.Winform
             {
                 Debug.WriteLine("State changed to " + _twain.State + " on thread " + Thread.CurrentThread.ManagedThreadId);
             };
+            _twain.TransferError += (s, e) =>
+            {
+                Debug.WriteLine("Got xfer error on thread " + Thread.CurrentThread.ManagedThreadId);
+            };
             _twain.DataTransferred += (s, e) =>
             {
                 Debug.WriteLine("Transferred data event on thread " + Thread.CurrentThread.ManagedThreadId);
@@ -223,7 +227,7 @@ namespace Tester.Winform
 
                 _stopScan = false;
 
-                if (_twain.CurrentSource.SupportedCaps.Contains(CapabilityId.CapUIControllable))
+                if (_twain.CurrentSource.CapUIControllable.IsSupported)//.SupportedCaps.Contains(CapabilityId.CapUIControllable))
                 {
                     // hide scanner ui if possible
                     if (_twain.CurrentSource.Enable(SourceEnableMode.NoUI, false, this.Handle) == ReturnCode.Success)
@@ -292,8 +296,10 @@ namespace Tester.Winform
         private void LoadSourceCaps()
         {
             var src = _twain.CurrentSource;
-            var caps = src.SupportedCaps;
             _loadingCaps = true;
+
+            var test = src.SupportedCaps;
+
             if (groupDepth.Enabled = src.ICapPixelType.IsSupported)
             {
                 LoadDepth(src.ICapPixelType);
@@ -311,7 +317,7 @@ namespace Tester.Winform
             {
                 LoadPaperSize(src.ICapSupportedSizes);
             }
-            btnAllSettings.Enabled = caps.Contains(CapabilityId.CapEnableDSUIOnly);
+            btnAllSettings.Enabled = src.CapEnableDSUIOnly.IsSupported;
             _loadingCaps = false;
         }