Merge branch '3.5.0'

.gitignore

@@ -59,5 +59,7 @@ AndroidNative/.gradle/
 AndroidNative/gradlew
 AndroidNative/gradlew.bat
 !EmbeddingTestBeds/Embedding.iOS/*.designer.cs
+*.nupkg
+*.pdb
 # temporary vim files
 *.swp

.nuspec/Xamarin.Forms.nuspec

@@ -26,6 +26,7 @@
         <dependency id="Xamarin.Android.Support.v7.AppCompat" version="28.0.0-preview8"/>
         <dependency id="Xamarin.Android.Support.v7.CardView" version="28.0.0-preview8"/>
         <dependency id="Xamarin.Android.Support.v7.MediaRouter" version="28.0.0-preview8"/>
+        <dependency id="Xamarin.Android.Support.CustomTabs" version="28.0.0-preview8"/>
       </group>
       <group targetFramework="uap10.0">
         <dependency id="NETStandard.Library" version="2.0.1"/>

XFCorePostProcessor.Tasks/FixXFCoreAssembly.cs

@@ -36,7 +36,7 @@ namespace XFCorePostProcessor.Tasks
 				var module = assemblyDefinition.MainModule;
 				if(resourceLoader.GetMethods().Count(md=>md.Name == "get_ResourceProvider") > 1) {
 					Log.LogMessage("  already executed");
-					return false;
+					return true;
 				}
 				var methodDef = new MethodDefinition("get_ResourceProvider",
 													 MethodAttributes.Static | MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.HideBySig,

Xamarin.Forms.Build.Tasks/MethodDefinitionExtensions.cs

@@ -51,5 +51,16 @@ namespace Xamarin.Forms.Build.Tasks
 			var t = ((GenericInstanceType)declaringTypeRef).GenericArguments[((GenericParameter)self.ReturnType).Position];
 			return t;
 		}
+
+		public static bool HasCustomAttributes(this MethodDefinition self, TypeReference attribute)
+		{
+			if (!self.HasCustomAttributes)
+				return false;
+			foreach (var arg in self.CustomAttributes) {
+				if (TypeRefComparer.Default.Equals(arg.AttributeType, attribute))
+					return true;
+			}
+			return false;
+		}
 	}
 }

Xamarin.Forms.Build.Tasks/SetPropertiesVisitor.cs

@@ -214,8 +214,7 @@ namespace Xamarin.Forms.Build.Tasks
 		public static bool TryGetPropertyName(INode node, INode parentNode, out XmlName name)
 		{
 			name = default(XmlName);
-			var parentElement = parentNode as IElementNode;
-			if (parentElement == null)
+			if (!(parentNode is IElementNode parentElement))
 				return false;
 			foreach (var kvp in parentElement.Properties)
 			{
@@ -229,8 +228,7 @@ namespace Xamarin.Forms.Build.Tasks
 
 		static bool IsCollectionItem(INode node, INode parentNode)
 		{
-			var parentList = parentNode as IListNode;
-			if (parentList == null)
+			if (!(parentNode is IListNode parentList))
 				return false;
 			return parentList.CollectionItems.Contains(node);
 		}
@@ -360,14 +358,12 @@ namespace Xamarin.Forms.Build.Tasks
 			//TODO support casting operators
 			var module = context.Module;
 
-			INode pathNode;
-			if (!node.Properties.TryGetValue(new XmlName("", "Path"), out pathNode) && node.CollectionItems.Any())
-				pathNode = node.CollectionItems [0];
+			if (!node.Properties.TryGetValue(new XmlName("", "Path"), out INode pathNode) && node.CollectionItems.Any())
+				pathNode = node.CollectionItems[0];
 			var path = (pathNode as ValueNode)?.Value as string;
-			BindingMode declaredmode;
 			if (   !node.Properties.TryGetValue(new XmlName("", "Mode"), out INode modeNode)
-			    || !Enum.TryParse((modeNode as ValueNode)?.Value as string, true, out declaredmode))
-				declaredmode = BindingMode.TwoWay;	//meaning the mode isn't specified in the Binding extension. generate getters, setters, handlers
+				|| !Enum.TryParse((modeNode as ValueNode)?.Value as string, true, out BindingMode declaredmode))
+				declaredmode = BindingMode.TwoWay;  //meaning the mode isn't specified in the Binding extension. generate getters, setters, handlers
 
 			INode dataTypeNode = null;
 			IElementNode n = node;
@@ -376,8 +372,7 @@ namespace Xamarin.Forms.Build.Tasks
 					break;
 				n = n.Parent as IElementNode;
 			}
-			var dataType = (dataTypeNode as ValueNode)?.Value as string;
-			if (dataType == null)
+			if (!((dataTypeNode as ValueNode)?.Value is string dataType))
 				yield break; //throw
 
 			var prefix = dataType.Contains(":") ? dataType.Substring(0, dataType.IndexOf(":", StringComparison.Ordinal)) : "";
@@ -398,17 +393,22 @@ namespace Xamarin.Forms.Build.Tasks
 				tPropertyRef = lastProp.property.ResolveGenericPropertyType(lastProp.propDeclTypeRef, module);
 			}
 			tPropertyRef = module.ImportReference(tPropertyRef);
-
-			var funcRef = module.ImportReference(module.ImportReference(("mscorlib", "System", "Func`2")).MakeGenericInstanceType(new [] { tSourceRef, tPropertyRef }));
+			var valuetupleRef = context.Module.ImportReference(module.ImportReference(("mscorlib", "System", "ValueTuple`2")).MakeGenericInstanceType(new[] { tPropertyRef, module.TypeSystem.Boolean }));
+			var funcRef = module.ImportReference(module.ImportReference(("mscorlib", "System", "Func`2")).MakeGenericInstanceType(new [] { tSourceRef, valuetupleRef }));
 			var actionRef = module.ImportReference(module.ImportReference(("mscorlib", "System", "Action`2")).MakeGenericInstanceType(new [] { tSourceRef, tPropertyRef }));
 			var funcObjRef = module.ImportReference(module.ImportReference(("mscorlib", "System", "Func`2")).MakeGenericInstanceType(new [] { tSourceRef, module.TypeSystem.Object }));
 			var tupleRef = module.ImportReference(module.ImportReference(("mscorlib", "System", "Tuple`2")).MakeGenericInstanceType(new [] { funcObjRef, module.TypeSystem.String}));
 			var typedBindingRef = module.ImportReference(module.ImportReference(("Xamarin.Forms.Core", "Xamarin.Forms.Internals", "TypedBinding`2")).MakeGenericInstanceType(new [] { tSourceRef, tPropertyRef}));
 
-			var ctorInfo =  module.ImportReference(typedBindingRef.ResolveCached().Methods.FirstOrDefault(md => md.IsConstructor && !md.IsStatic && md.Parameters.Count == 3 ));
+			//FIXME: make sure the non-deprecated one is used
+			var ctorInfo =  module.ImportReference(typedBindingRef.ResolveCached().Methods.FirstOrDefault(md => 
+					   md.IsConstructor
+					&& !md.IsStatic
+					&& md.Parameters.Count == 3
+					&& !md.HasCustomAttributes (module.ImportReference(("mscorlib", "System", "ObsoleteAttribute")))));
 			var ctorinforef = ctorInfo.MakeGeneric(typedBindingRef, funcRef, actionRef, tupleRef);
 
-			yield return Instruction.Create(OpCodes.Ldloc, bindingExt);
+			yield return Create(Ldloc, bindingExt);
 			foreach (var instruction in CompiledBindingGetGetter(tSourceRef, tPropertyRef, properties, node, context))
 				yield return instruction;
 			if (declaredmode != BindingMode.OneTime && declaredmode != BindingMode.OneWay) { //if the mode is explicitly 1w, or 1t, no need for setters
@@ -421,8 +421,8 @@ namespace Xamarin.Forms.Build.Tasks
 					yield return instruction;
 			} else
 				yield return Create(Ldnull);
-			yield return Instruction.Create(OpCodes.Newobj, module.ImportReference(ctorinforef));
-			yield return Instruction.Create(OpCodes.Callvirt, module.ImportPropertySetterReference(("Xamarin.Forms.Xaml", "Xamarin.Forms.Xaml", "BindingExtension"), propertyName: "TypedBinding"));
+			yield return Create(Newobj, module.ImportReference(ctorinforef));
+			yield return Create(Callvirt, module.ImportPropertySetterReference(("Xamarin.Forms.Xaml", "Xamarin.Forms.Xaml", "BindingExtension"), propertyName: "TypedBinding"));
 		}
 
 		static IList<(PropertyDefinition property, TypeReference propDeclTypeRef, string indexArg)> ParsePath(string path, TypeReference tSourceRef, IXmlLineInfo lineInfo, ModuleDefinition module)
@@ -476,32 +476,44 @@ namespace Xamarin.Forms.Build.Tasks
 
 		static IEnumerable<Instruction> CompiledBindingGetGetter(TypeReference tSourceRef, TypeReference tPropertyRef, IList<(PropertyDefinition property, TypeReference propDeclTypeRef, string indexArg)> properties, ElementNode node, ILContext context)
 		{
-//			.method private static hidebysig default string '<Main>m__0' (class ViewModel vm)  cil managed
-//			{
-//				.custom instance void class [mscorlib]System.Runtime.CompilerServices.CompilerGeneratedAttribute::'.ctor'() =  (01 00 00 00 ) // ...
-//
-//				IL_0000:  ldarg.0 
-//				IL_0001:  callvirt instance class ViewModel class ViewModel::get_Model()
-//				IL_0006:  callvirt instance string class ViewModel::get_Text()
-//				IL_0006:  ret
-//			}
+//				.method private static hidebysig default valuetype[mscorlib] System.ValueTuple`2<string, bool> '<Main>m__0' (class ViewModel A_0)  cil managed
+//				{
+//					.custom instance void class [mscorlib] System.Runtime.CompilerServices.CompilerGeneratedAttribute::'.ctor'() =  (01 00 00 00 ) // ....
+//					IL_0000:  ldarg.0 
+//					IL_0001:  dup
+//					IL_0002:  ldnull
+//					IL_0003:  ceq
+//					IL_0005:  brfalse IL_0013
+//					IL_000a:  pop
+//					IL_000b:  ldnull
+//					IL_000c:  ldc.i4.0 
+//					IL_000d:  newobj instance void valuetype[mscorlib]System.ValueTuple`2<string, bool>::'.ctor'(!0, !1)
+//					IL_0012:  ret
+//					IL_0013:  nop
+//					IL_0014:  call instance string class ViewModel::get_Text()
+//					IL_0019:  ldc.i4.1 
+//					IL_001a:  newobj instance void valuetype[mscorlib]System.ValueTuple`2<string, bool>::'.ctor'(!0, !1)
+//					IL_001f:  ret
+//				}
 
 			var module = context.Module;
+			var tupleRef = module.ImportReference(module.ImportReference(("mscorlib", "System", "ValueTuple`2")).MakeGenericInstanceType(new[] { tPropertyRef, module.TypeSystem.Boolean }));
+			var tupleCtorRef = module.ImportCtorReference(tupleRef, 2);
+			tupleCtorRef = module.ImportReference(tupleCtorRef.ResolveGenericParameters(tupleRef, module));
 			var getter = new MethodDefinition($"<{context.Body.Method.Name}>typedBindingsM__{typedBindingCount++}",
 											  MethodAttributes.Private | MethodAttributes.HideBySig | MethodAttributes.Static,
-											  tPropertyRef) {
-				Parameters = {
-					new ParameterDefinition(tSourceRef)
-				},
-				CustomAttributes = {
-					new CustomAttribute (module.ImportCtorReference(("mscorlib", "System.Runtime.CompilerServices", "CompilerGeneratedAttribute"), parameterTypes: null))
-				}
+											  tupleRef) {
+				Parameters = { new ParameterDefinition(tSourceRef) },
+				CustomAttributes = { new CustomAttribute (module.ImportCtorReference(("mscorlib", "System.Runtime.CompilerServices", "CompilerGeneratedAttribute"), parameterTypes: null)) }
 			};
+
 			getter.Body.InitLocals = true;
 			var il = getter.Body.GetILProcessor();
 
 			if (properties == null || properties.Count == 0) { //return self
 				il.Emit(Ldarg_0);
+				il.Emit(Ldc_I4_1); //true
+				il.Emit(Newobj, tupleCtorRef);
 				il.Emit(Ret);
 			}
 			else {
@@ -510,39 +522,60 @@ namespace Xamarin.Forms.Build.Tasks
 				else
 					il.Emit(Ldarg_0);
 
-				foreach (var propTuple in properties) {
-					var property = propTuple.property;
-					var propDeclType = propTuple.propDeclTypeRef;
-					var indexerArg = propTuple.indexArg;
-					if (indexerArg != null) {
-						if (property.GetMethod.Parameters[0].ParameterType == module.TypeSystem.String)
-							il.Emit(Ldstr, indexerArg);
-						else if (property.GetMethod.Parameters[0].ParameterType == module.TypeSystem.Int32) {
-							if (!int.TryParse(indexerArg, out int index))
-								throw new XamlParseException($"Binding: {indexerArg} could not be parsed as an index for a {property.Name}", node as IXmlLineInfo);
-							il.Emit(Ldc_I4, index);
+				for (int i = 0; i < properties.Count; i++) {
+					(PropertyDefinition property, TypeReference propDeclTypeRef, string indexArg) = properties[i];
+
+					if (!property.PropertyType.IsValueType) { //if part of the path is null, return (default(T), false)
+						var nop = Create(Nop);
+						il.Emit(Dup);
+						il.Emit(Ldnull);
+						il.Emit(Ceq);
+						il.Emit(Brfalse, nop);
+						il.Emit(Pop);
+						if (tPropertyRef.IsValueType) {
+							var defaultValueVarDef = new VariableDefinition(tPropertyRef);
+							getter.Body.Variables.Add(defaultValueVarDef);
+							il.Emit(Ldloca_S, defaultValueVarDef);
+							il.Emit(Initobj, tPropertyRef);
+							il.Emit(Ldloc, defaultValueVarDef);
 						}
+						else
+							il.Emit(Ldnull);
+						il.Emit(Ldc_I4_0); //false
+
+						il.Emit(Newobj, tupleCtorRef);
+						il.Emit(Ret);
+						il.Append(nop);
 					}
-					var getMethod = module.ImportReference(property.GetMethod);
-					getMethod = module.ImportReference(getMethod.ResolveGenericParameters(propDeclType, module));
+
+					if (indexArg != null) {
+						if (property.GetMethod.Parameters[0].ParameterType == module.TypeSystem.String)
+							il.Emit(Ldstr, indexArg);
+						else if (property.GetMethod.Parameters[0].ParameterType == module.TypeSystem.Int32 && int.TryParse(indexArg, out int index))
+							il.Emit(Ldc_I4, index);
+						else
+							throw new XamlParseException($"Binding: {indexArg} could not be parsed as an index for a {property.Name}", node as IXmlLineInfo);
+					}
+
+					var getMethod = module.ImportReference((module.ImportReference(property.GetMethod)).ResolveGenericParameters(propDeclTypeRef, module));
 
 					if (property.GetMethod.IsVirtual)
 						il.Emit(Callvirt, getMethod);
 					else
 						il.Emit(Call, getMethod);
-					}
-
+				}
+				il.Emit(Ldc_I4_1); //true
+				il.Emit(Newobj, tupleCtorRef);
 				il.Emit(Ret);
 			}
 			context.Body.Method.DeclaringType.Methods.Add(getter);
 
-//			IL_0007:  ldnull
-//			IL_0008:  ldftn string class Test::'<Main>m__0'(class ViewModel)
-//			IL_000e:  newobj instance void class [mscorlib]System.Func`2<class ViewModel, string>::'.ctor'(object, native int)
-
+//			IL_02fa:  ldnull
+//			IL_02fb:  ldftn valuetype[mscorlib]System.ValueTuple`2 <string,bool> class Test::'<Main>m__0'(class ViewModel)
+//			IL_0301:  newobj instance void class [mscorlib] System.Func`2<class ViewModel, valuetype[mscorlib] System.ValueTuple`2<string, bool>>::'.ctor'(object, native int)
 			yield return Create(Ldnull);
 			yield return Create(Ldftn, getter);
-			yield return Create(Newobj, module.ImportCtorReference(("mscorlib", "System", "Func`2"), paramCount: 2, classArguments: new[] { tSourceRef, tPropertyRef }));
+			yield return Create(Newobj, module.ImportCtorReference(("mscorlib", "System", "Func`2"), paramCount: 2, classArguments: new[] { tSourceRef, tupleRef }));
 		}
 
 		static IEnumerable<Instruction> CompiledBindingGetSetter(TypeReference tSourceRef, TypeReference tPropertyRef, IList<(PropertyDefinition property, TypeReference propDeclTypeRef, string indexArg)> properties, ElementNode node, ILContext context)
@@ -552,16 +585,16 @@ namespace Xamarin.Forms.Build.Tasks
 				yield break;
 			}
 
-			//			.method private static hidebysig default void '<Main>m__1' (class ViewModel vm, string s)  cil managed
-			//			{
-			//				.custom instance void class [mscorlib]System.Runtime.CompilerServices.CompilerGeneratedAttribute::'.ctor'() =  (01 00 00 00 ) // ....
-			//
-			//				IL_0000:  ldarg.0 
-			//				IL_0001:  callvirt instance class ViewModel class ViewModel::get_Model()
-			//				IL_0006:  ldarg.1 
-			//				IL_0007:  callvirt instance void class ViewModel::set_Text(string)
-			//				IL_000c:  ret
-			//			}
+//			.method private static hidebysig default void '<Main>m__1' (class ViewModel vm, string s)  cil managed
+//			{
+//				.custom instance void class [mscorlib]System.Runtime.CompilerServices.CompilerGeneratedAttribute::'.ctor'() =  (01 00 00 00 ) // ....
+//
+//				IL_0000:  ldarg.0 
+//				IL_0001:  callvirt instance class ViewModel class ViewModel::get_Model()
+//				IL_0006:  ldarg.1 
+//				IL_0007:  callvirt instance void class ViewModel::set_Text(string)
+//				IL_000c:  ret
+//			}
 
 			var module = context.Module;
 			var setter = new MethodDefinition($"<{context.Body.Method.Name}>typedBindingsM__{typedBindingCount++}",

Xamarin.Forms.Build.Tasks/XamlCTask.cs

@@ -48,14 +48,14 @@ namespace Xamarin.Forms.Build.Tasks
 			var resolver = DefaultAssemblyResolver ?? new XamlCAssemblyResolver();
 			if (resolver is XamlCAssemblyResolver xamlCResolver) {
 				if (!string.IsNullOrEmpty(DependencyPaths)) {
-					foreach (var dep in DependencyPaths.Split(';')) {
+					foreach (var dep in DependencyPaths.Split(';').Distinct()) {
 						LoggingHelper.LogMessage(Low, $"{new string(' ', 2)}Adding searchpath {dep}");
 						xamlCResolver.AddSearchDirectory(dep);
 					}
 				}
 
 				if (!string.IsNullOrEmpty(ReferencePath)) {
-					var paths = ReferencePath.Replace("//", "/").Split(';');
+					var paths = ReferencePath.Replace("//", "/").Split(';').Distinct();
 					foreach (var p in paths) {
 						var searchpath = Path.GetDirectoryName(p);
 						LoggingHelper.LogMessage(Low, $"{new string(' ', 2)}Adding searchpath {searchpath}");

Xamarin.Forms.Build.Tasks/XamlGenerator.cs

@@ -385,20 +385,20 @@ namespace Xamarin.Forms.Build.Tasks
 			_xmlnsDefinitions = new List<XmlnsDefinitionAttribute>();
 			_xmlnsModules = new Dictionary<string, ModuleDefinition>();
 
-			if (string.IsNullOrEmpty(this.References))
+			if (string.IsNullOrEmpty(References))
 				return;
 
-			string[] paths = this.References.Split(';');
+			string[] paths = References.Split(';').Distinct().ToArray();
 
-			foreach ( var path in paths ) {
+			foreach (var path in paths) {
 				string asmName = Path.GetFileName(path);
-				if ( AssemblyIsSystem(asmName) )
+				if (AssemblyIsSystem(asmName))
 					// Skip the myriad "System." assemblies and others
 					continue;				
 
 				using (var asmDef = AssemblyDefinition.ReadAssembly(path)) {
-					foreach ( var ca in asmDef.CustomAttributes ) {
-						if ( ca.AttributeType.FullName == typeof(XmlnsDefinitionAttribute).FullName) {
+					foreach (var ca in asmDef.CustomAttributes) {
+						if (ca.AttributeType.FullName == typeof(XmlnsDefinitionAttribute).FullName) {
 							_xmlnsDefinitions.Add(ca.GetXmlnsDefinition(asmDef));
 							_xmlnsModules[asmDef.FullName] = asmDef.MainModule;
 						}

Xamarin.Forms.Core.UnitTests/ShellTests.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Threading.Tasks;
 using NUnit.Framework;
 using Xamarin.Forms.Internals;
 
@@ -76,15 +77,26 @@ namespace Xamarin.Forms.Core.UnitTests
 			Assert.AreEqual(shellItem, shell.CurrentItem);
 		}
 
-		ShellSection MakeSimpleShellSection (string route, string contentRoute)
+		ShellSection MakeSimpleShellSection(string route, string contentRoute)
+		{
+			return MakeSimpleShellSection(route, contentRoute, new ShellTestPage());
+		}
+
+		ShellSection MakeSimpleShellSection (string route, string contentRoute, ContentPage contentPage)
 		{
 			var shellSection = new ShellSection();
 			shellSection.Route = route;
-			var shellContent = new ShellContent { Content = new ContentPage(), Route = contentRoute };
+			var shellContent = new ShellContent { Content = contentPage, Route = contentRoute };
 			shellSection.Items.Add(shellContent);
 			return shellSection;
 		}
 
+		[QueryProperty("SomeQueryParameter", "SomeQueryParameter")]
+		public class ShellTestPage : ContentPage
+		{
+			public string SomeQueryParameter { get; set; }
+		}
+
 		[Test]
 		public void SimpleGoTo()
 		{
@@ -115,6 +127,65 @@ namespace Xamarin.Forms.Core.UnitTests
 			Assert.That(shell.CurrentState.Location.ToString(), Is.EqualTo("app:///s/two/tabfour/content/"));
 		}
 
+
+
+		[Test]
+		public async Task NavigationWithQueryStringWhenPageMatchesBindingContext()
+		{
+			var shell = new Shell();
+			shell.Route = "s";
+
+			var one = new ShellItem { Route = "one" };
+			var two = new ShellItem { Route = "two" };
+
+			var tabone = MakeSimpleShellSection("tabone", "content");
+			var tabfour = MakeSimpleShellSection("tabfour", "content", null);
+
+			one.Items.Add(tabone);
+			two.Items.Add(tabfour);
+
+			shell.Items.Add(one);
+			shell.Items.Add(two);
+
+			ShellTestPage pagetoTest = new ShellTestPage();
+			await shell.GoToAsync(new ShellNavigationState($"app:///s/two/tabfour/content?{nameof(ShellTestPage.SomeQueryParameter)}=1234"));
+			two.CurrentItem.CurrentItem.ContentTemplate = new DataTemplate(() =>
+			{
+				pagetoTest = new ShellTestPage();
+				pagetoTest.BindingContext = pagetoTest;
+				return pagetoTest;
+			});
+
+			
+			var page = (two.CurrentItem.CurrentItem as IShellContentController).GetOrCreateContent();
+			Assert.AreEqual("1234", (page as ShellTestPage).SomeQueryParameter);
+
+		}
+
+
+		[Test]
+		public async Task NavigationWithQueryStringAndNoDataTemplate()
+		{
+			var shell = new Shell();
+			shell.Route = "s";
+
+			var one = new ShellItem { Route = "one" };
+			var two = new ShellItem { Route = "two" };
+
+			var tabone = MakeSimpleShellSection("tabone", "content");
+			var tabfour = MakeSimpleShellSection("tabfour", "content");
+
+			one.Items.Add(tabone);
+			two.Items.Add(tabfour);
+
+			shell.Items.Add(one);
+			shell.Items.Add(two);
+
+			await shell.GoToAsync(new ShellNavigationState($"app:///s/two/tabfour/content?{nameof(ShellTestPage.SomeQueryParameter)}=1234"));
+			Assert.AreEqual("1234", (two.CurrentItem.CurrentItem.Content as ShellTestPage).SomeQueryParameter);
+
+		}
+
 		[Test]
 		public void CancelNavigation()
 		{

Xamarin.Forms.Core.UnitTests/TypedBindingUnitTests.cs

@@ -51,7 +51,7 @@ namespace Xamarin.Forms.Core.UnitTests
 		[Test]
 		public void InvalidCtor()
 		{
-			Assert.Throws<ArgumentNullException>(() => new TypedBinding<MockViewModel, string>(null, (mvm, s) => mvm.Text = s, null), "Allowed null getter");
+			Assert.Throws<ArgumentNullException>(() => new TypedBinding<MockViewModel, string>((Func<MockViewModel, string>)null, (mvm, s) => mvm.Text = s, null), "Allowed null getter");
 		}
 
 		[Test, NUnit.Framework.Category("[Binding] Set Value")]

Xamarin.Forms.Core/Shell/BaseShellItem.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.ComponentModel;
 using Xamarin.Forms.Internals;
 
 namespace Xamarin.Forms
@@ -104,5 +103,15 @@ namespace Xamarin.Forms
 		}
 		bool IFlowDirectionController.ApplyEffectiveFlowDirectionToChildContainer => true;
 		double IFlowDirectionController.Width => (Parent as VisualElement)?.Width ?? 0;
+
+
+		internal virtual void ApplyQueryAttributes(IDictionary<string, string> query)
+		{
+		}
+	}
+
+	public interface IQueryAttributable
+	{
+		void ApplyQueryAttributes(IDictionary<string, string> query);
 	}
 }

Xamarin.Forms.Core/Shell/QueryPropertyAttribute.cs

@@ -5,9 +5,8 @@ namespace Xamarin.Forms
 	[AttributeUsage(AttributeTargets.Class)]
 	public class QueryPropertyAttribute : Attribute
 	{
-		public string Name { get; private set; }
-
-		public string QueryId { get; private set; }
+		public string Name { get;  }
+		public string QueryId { get; }
 
 		public QueryPropertyAttribute(string name, string queryId)
 		{

Xamarin.Forms.Core/Shell/Shell.cs

@@ -402,89 +402,35 @@ namespace Xamarin.Forms
 				prefix = route + ".";
 			}
 
-			var type = element.GetType();
-			var typeInfo = type.GetTypeInfo();
-#if NETSTANDARD1_0
-			var effectAttributes = typeInfo.GetCustomAttributes(typeof(QueryPropertyAttribute), true).ToArray();
-#else
-			var effectAttributes = typeInfo.GetCustomAttributes(typeof(QueryPropertyAttribute), true);
-#endif
-
-			if (effectAttributes.Length == 0)
-				return;
-
-			foreach (var a in effectAttributes)
-			{
-				if (a is QueryPropertyAttribute attrib)
-				{
-					if (query.TryGetValue(prefix + attrib.QueryId, out var value))
-					{
-						PropertyInfo prop = type.GetRuntimeProperty(attrib.Name);
-
-						if (prop != null && prop.CanWrite && prop.SetMethod.IsPublic)
-						{
-							prop.SetValue(element, value);
-						}
-					}
-				}
-			}
-		}
-
-		static string GenerateQueryString(Dictionary<string, string> queryData)
-		{
-			if (queryData.Count == 0)
-				return string.Empty;
-			string result = "?";
-
-			bool addAnd = false;
-			foreach (var kvp in queryData)
-			{
-				if (addAnd)
-					result += "&";
-				result += kvp.Key + "=" + kvp.Value;
-				addAnd = true;
+			//if the lastItem is implicitly wrapped, get the actual ShellContent
+			if (isLastItem) {
+				if (element is ShellItem shellitem && shellitem.Items.FirstOrDefault() is ShellSection section)
+					element = section;
+				if (element is ShellSection shellsection && shellsection.Items.FirstOrDefault() is ShellContent content)
+					element = content;
+				if (element is ShellContent shellcontent && shellcontent.Content is Element e)
+					element = e;
 			}
 
-			return result;
-		}
-
-		static void GetQueryStringData(Element element, bool isLastItem, Dictionary<string, string> result)
-		{
-			string prefix = string.Empty;
-			if (!isLastItem)
+			if (!(element is BaseShellItem baseShellItem))
 			{
-				var route = Routing.GetRoute(element);
-				if (string.IsNullOrEmpty(route) || route.StartsWith(Routing.ImplicitPrefix, StringComparison.Ordinal))
+				baseShellItem = element?.Parent as BaseShellItem;
+				if(baseShellItem == null)
 					return;
-				prefix = route + ".";
 			}
 
-			var type = element.GetType();
-			var typeInfo = type.GetTypeInfo();
-
-#if NETSTANDARD1_0
-			var effectAttributes = typeInfo.GetCustomAttributes(typeof(QueryPropertyAttribute), true).ToArray();
-#else
-			var effectAttributes = type.GetCustomAttributes(typeof(QueryPropertyAttribute), true);
-#endif
-
-			if (effectAttributes.Length == 0)
-				return;
-
-			for (int i = 0; i < effectAttributes.Length; i++)
-			{
-				if (effectAttributes[i] is QueryPropertyAttribute attrib)
-				{
-					PropertyInfo prop = type.GetRuntimeProperty(attrib.Name);
-
-					if (prop != null && prop.CanRead && prop.GetMethod.IsPublic)
-					{
-						var val = (string)prop.GetValue(element);
-						var key = isLastItem ? prefix + attrib.QueryId : attrib.QueryId;
-						result[key] = val;
-					}
-				}
+			//filter the query to only apply the keys with matching prefix
+			var filteredQuery = new Dictionary<string, string>(query.Count);
+			foreach (var q in query) {
+				if (!q.Key.StartsWith(prefix, StringComparison.Ordinal))
+					continue;
+				var key = q.Key.Substring(prefix.Length);
+				if (key.Contains("."))
+					continue;
+				filteredQuery.Add(key, q.Value);
 			}
+
+			baseShellItem.ApplyQueryAttributes(filteredQuery);
 		}
 
 		ShellNavigationState GetNavigationState(ShellItem shellItem, ShellSection shellSection, ShellContent shellContent, IReadOnlyList<Page> sectionStack)
@@ -494,8 +440,6 @@ namespace Xamarin.Forms
 
 			bool stackAtRoot = sectionStack == null || sectionStack.Count <= 1;
 
-			GetQueryStringData(this, false, queryData);
-
 			if (shellItem != null)
 			{
 				var shellItemRoute = shellItem.Route;
@@ -505,8 +449,6 @@ namespace Xamarin.Forms
 					stateBuilder.Append("/");
 				}
 
-				GetQueryStringData(shellItem, shellSection == null, queryData);
-
 				if (shellSection != null)
 				{
 					var shellSectionRoute = shellSection.Route;
@@ -516,8 +458,6 @@ namespace Xamarin.Forms
 						stateBuilder.Append("/");
 					}
 
-					GetQueryStringData(shellSection, shellContent == null && stackAtRoot, queryData);
-
 					if (shellContent != null)
 					{
 						var shellContentRoute = shellContent.Route;
@@ -526,8 +466,6 @@ namespace Xamarin.Forms
 							stateBuilder.Append(shellContentRoute);
 							stateBuilder.Append("/");
 						}
-
-						GetQueryStringData(shellContent, stackAtRoot, queryData);
 					}
 
 					if (!stackAtRoot)
@@ -536,7 +474,6 @@ namespace Xamarin.Forms
 						{
 							var page = sectionStack[i];
 							stateBuilder.Append(Routing.GetRoute(page));
-							GetQueryStringData(page, i == sectionStack.Count - 1, queryData);
 							if (i < sectionStack.Count - 1)
 								stateBuilder.Append("/");
 						}
@@ -544,7 +481,6 @@ namespace Xamarin.Forms
 				}
 			}
 
-			stateBuilder.Append(GenerateQueryString(queryData));
 			return stateBuilder.ToString();
 		}
 
@@ -800,15 +736,12 @@ namespace Xamarin.Forms
 		protected virtual void OnNavigated(ShellNavigatedEventArgs args)
 		{
 			if (_accumulateNavigatedEvents)
-			{
 				_accumulatedEvent = args;
-			}
-			else
-			{
-				if (args.Current.Location.AbsolutePath != _lastNavigating.Location.AbsolutePath)
-				{
-					throw new Exception();
-				}
+			else {
+				/* Removing this check for now as it doesn't properly cover all implicit scenarios
+				 * if (args.Current.Location.AbsolutePath.TrimEnd('/') != _lastNavigating.Location.AbsolutePath.TrimEnd('/'))
+					throw new InvalidOperationException($"Navigation: Current location doesn't match navigation uri {args.Current.Location.AbsolutePath} != {_lastNavigating.Location.AbsolutePath}");
+					*/
 				Navigated?.Invoke(this, args);
 				//System.Diagnostics.Debug.WriteLine("Navigated: " + args.Current.Location);
 			}

Xamarin.Forms.Core/Shell/ShellContent.cs

@@ -1,6 +1,13 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Collections.Specialized;
+
+#if NETSTANDARD1_0
+using System.Linq;
+#endif
+
+using System.Reflection;
 using Xamarin.Forms.Internals;
 
 namespace Xamarin.Forms
@@ -8,15 +15,29 @@ namespace Xamarin.Forms
 	[ContentProperty("Content")]
 	public class ShellContent : BaseShellItem, IShellContentController
 	{
-		#region PropertyKeys
-
 		static readonly BindablePropertyKey MenuItemsPropertyKey =
 			BindableProperty.CreateReadOnly(nameof(MenuItems), typeof(MenuItemCollection), typeof(ShellContent), null,
 				defaultValueCreator: bo => new MenuItemCollection());
 
-		#endregion PropertyKeys
+		public static readonly BindableProperty MenuItemsProperty = MenuItemsPropertyKey.BindableProperty;
 
-		#region IShellContentController
+		public static readonly BindableProperty ContentProperty =
+			BindableProperty.Create(nameof(Content), typeof(object), typeof(ShellContent), null, BindingMode.OneTime, propertyChanged: OnContentChanged);
+
+		public static readonly BindableProperty ContentTemplateProperty =
+			BindableProperty.Create(nameof(ContentTemplate), typeof(DataTemplate), typeof(ShellContent), null, BindingMode.OneTime);
+
+		public MenuItemCollection MenuItems => (MenuItemCollection)GetValue(MenuItemsProperty);
+
+		public object Content {
+			get => GetValue(ContentProperty);
+			set => SetValue(ContentProperty, value);
+		}
+
+		public DataTemplate ContentTemplate {
+			get => (DataTemplate)GetValue(ContentTemplateProperty);
+			set => SetValue(ContentTemplateProperty, value);
+		}
 
 		Page IShellContentController.Page => ContentCache;
 
@@ -40,6 +61,12 @@ namespace Xamarin.Forms
 			if (result != null && result.Parent != this)
 				OnChildAdded(result);
 
+
+			if (_delayedQueryParams != null && result  != null) {
+				ApplyQueryAttributes(result, _delayedQueryParams);
+				_delayedQueryParams = null;
+			}
+
 			return result;
 		}
 
@@ -52,16 +79,6 @@ namespace Xamarin.Forms
 			}
 		}
 
-		#endregion IShellContentController
-
-		public static readonly BindableProperty ContentProperty =
-			BindableProperty.Create(nameof(Content), typeof(object), typeof(ShellContent), null, BindingMode.OneTime, propertyChanged: OnContentChanged);
-
-		public static readonly BindableProperty ContentTemplateProperty =
-			BindableProperty.Create(nameof(ContentTemplate), typeof(DataTemplate), typeof(ShellContent), null, BindingMode.OneTime);
-
-		public static readonly BindableProperty MenuItemsProperty = MenuItemsPropertyKey.BindableProperty;
-
 		Page _contentCache;
 		IList<Element> _logicalChildren = new List<Element>();
 		ReadOnlyCollection<Element> _logicalChildrenReadOnly;
@@ -71,19 +88,7 @@ namespace Xamarin.Forms
 			((INotifyCollectionChanged)MenuItems).CollectionChanged += MenuItemsCollectionChanged;
 		}
 
-		public object Content
-		{
-			get { return GetValue(ContentProperty); }
-			set { SetValue(ContentProperty, value); }
-		}
 
-		public DataTemplate ContentTemplate
-		{
-			get { return (DataTemplate)GetValue(ContentTemplateProperty); }
-			set { SetValue(ContentTemplateProperty, value); }
-		}
-
-		public MenuItemCollection MenuItems => (MenuItemCollection)GetValue(MenuItemsProperty);
 		internal override ReadOnlyCollection<Element> LogicalChildrenInternal => _logicalChildrenReadOnly ?? (_logicalChildrenReadOnly = new ReadOnlyCollection<Element>(_logicalChildren));
 
 		Page ContentCache {
@@ -142,15 +147,53 @@ namespace Xamarin.Forms
 		void MenuItemsCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
 		{
 			if (e.NewItems != null)
-			{
 				foreach (Element el in e.NewItems)
 					OnChildAdded(el);
-			}
 
 			if (e.OldItems != null)
-			{
 				foreach (Element el in e.OldItems)
 					OnChildRemoved(el);
+		}
+
+		IDictionary<string, string> _delayedQueryParams;
+		internal override void ApplyQueryAttributes(IDictionary<string, string> query)
+		{
+			base.ApplyQueryAttributes(query);
+			ApplyQueryAttributes(this, query);
+
+			if (Content == null) {
+				_delayedQueryParams = query;
+				return;
+			}
+			ApplyQueryAttributes(Content as Page, query);
+		}
+
+		static void ApplyQueryAttributes(object content, IDictionary<string, string> query)
+		{
+			if (content is IQueryAttributable attributable)
+				attributable.ApplyQueryAttributes(query);
+
+			if (content is BindableObject bindable && bindable.BindingContext != null && content != bindable.BindingContext)
+				ApplyQueryAttributes(bindable.BindingContext, query);
+
+			var type = content.GetType();
+			var typeInfo = type.GetTypeInfo();
+#if NETSTANDARD1_0
+			var queryPropertyAttributes = typeInfo.GetCustomAttributes(typeof(QueryPropertyAttribute), true).ToArray();
+#else
+			var queryPropertyAttributes = typeInfo.GetCustomAttributes(typeof(QueryPropertyAttribute), true);
+#endif
+
+			if (queryPropertyAttributes.Length == 0)
+				return;
+
+			foreach (QueryPropertyAttribute attrib in queryPropertyAttributes) {
+				if (query.TryGetValue(attrib.QueryId, out var value)) {
+					PropertyInfo prop = type.GetRuntimeProperty(attrib.Name);
+
+					if (prop != null && prop.CanWrite && prop.SetMethod.IsPublic)
+						prop.SetValue(content, value);
+				}
 			}
 		}
 	}

Xamarin.Forms.Core/TypedBinding.cs

@@ -58,11 +58,19 @@ namespace Xamarin.Forms.Internals
 	[EditorBrowsable(EditorBrowsableState.Never)]
 	public sealed class TypedBinding<TSource, TProperty> : TypedBindingBase
 	{
-		readonly Func<TSource, TProperty> _getter;
+		readonly Func<TSource, (TProperty value, bool success)> _getter;
 		readonly Action<TSource, TProperty> _setter;
 		readonly PropertyChangedProxy [] _handlers;
 
+		[Obsolete("deprecated one. kept for backcompat")]
 		public TypedBinding(Func<TSource, TProperty> getter, Action<TSource, TProperty> setter, Tuple<Func<TSource, object>, string> [] handlers)
+				: this (s=>(getter(s), true), setter, handlers)
+		{
+			if (getter == null)
+				throw new ArgumentNullException(nameof(getter));
+		}
+
+		public TypedBinding(Func<TSource, (TProperty value, bool success)> getter, Action<TSource, TProperty> setter, Tuple<Func<TSource, object>, string>[] handlers)
 		{
 			_getter = getter ?? throw new ArgumentNullException(nameof(getter));
 			_setter = setter;
@@ -70,9 +78,9 @@ namespace Xamarin.Forms.Internals
 			if (handlers == null)
 				return;
 
-			_handlers = new PropertyChangedProxy [handlers.Length];
+			_handlers = new PropertyChangedProxy[handlers.Length];
 			for (var i = 0; i < handlers.Length; i++)
-				_handlers [i] = new PropertyChangedProxy(handlers [i].Item1, handlers [i].Item2, this);
+				_handlers[i] = new PropertyChangedProxy(handlers[i].Item1, handlers[i].Item2, this);
 		}
 
 		readonly WeakReference<object> _weakSource = new WeakReference<object>(null);
@@ -196,7 +204,9 @@ namespace Xamarin.Forms.Internals
 				var value = FallbackValue ?? property.GetDefaultValue(target);
 				if (isTSource) {
 					try {
-						value = GetSourceValue(_getter((TSource)sourceObject), property.ReturnType);
+						(var retval, bool success) = _getter((TSource)sourceObject);
+						if (success) //if the getter failed, return the FallbackValue
+							value = GetSourceValue(retval, property.ReturnType);
 					} catch (Exception ex) when (ex is NullReferenceException || ex is KeyNotFoundException || ex is IndexOutOfRangeException) {
 					}
 				}

Xamarin.Forms.Core/Xamarin.Forms.Core.csproj

@@ -18,7 +18,7 @@
 		<Compile Include="Internals\Legacy\**" />
 		<PackageReference Include="System.ComponentModel" Version="4.3.0" />
 		<PackageReference Include="System.Dynamic.Runtime" Version="4.3.0" />
-		<PackageReference Include="System.ValueTuple" Version="4.4.0" />
+		<PackageReference Include="System.ValueTuple" Version="4.5.0" />
 	</ItemGroup>
 	<Import Project="..\Xamarin.Flex\Xamarin.Flex.projitems" Label="Shared" Condition="Exists('..\Xamarin.Flex\Xamarin.Flex.projitems')" />
 	<UsingTask TaskName="XFCorePostProcessor.Tasks.FixXFCoreAssembly" AssemblyFile="..\XFCorePostProcessor.Tasks\bin\Debug\net461\XFCorePostProcessor.Tasks.dll" />

Xamarin.Forms.Platform.UAP/CellControl.cs

@@ -235,6 +235,9 @@ namespace Xamarin.Forms.Platform.UWP
 
 		void OnDataContextChanged(FrameworkElement sender, DataContextChangedEventArgs args)
 		{
+			if (args.NewValue == null)
+				return;
+
 			// We don't want to set the Cell until the ListView is realized, just in case the 
 			// Cell has an ItemTemplate. Instead, we'll store the new data item, and it will be
 			// set on MeasureOverrideDelegate. However, if the parent is a TableView, we'll already 

Xamarin.Forms.Platform.iOS/Renderers/BarAppearanceTrackerUtils.cs

@@ -1,44 +0,0 @@
-using System;
-
-namespace Xamarin.Forms.Platform.iOS
-{
-	public static class BarAppearanceTrackerUtils
-	{
-		public static Color UnblendColor(Color color)
-		{
-			// iOS is going to ignore any alpha mask on this color so we need
-			// to just assume its a solid color. We'll "blend" it with white.
-
-			var r = color.R;
-			var g = color.G;
-			var b = color.B;
-			var a = color.A;
-
-			r = (r * a) + (1 - a);
-			g = (g * a) + (1 - a);
-			b = (b * a) + (1 - a);
-
-			// Now iOS is going to blend with white at 86% opacity, so we need to "darken" the
-			// color we pass in order to compensate
-
-			r = UnblendBackgroundChannel(r, .863);
-			g = UnblendBackgroundChannel(g, .863);
-			b = UnblendBackgroundChannel(b, .863);
-
-			return new Color(r, g, b);
-		}
-
-		static double UnblendBackgroundChannel(double channel, double alpha)
-		{
-			// basically iOS is going to blend us with white to produce its final color,
-			// so we are going to apply the default blend in reverse to produce a true color.
-
-			// Unfortunately "unblending" only works for a subset of all possible values as you
-			// can get a negative number. This means that there is no source input value
-			// for which the requested color can be retreived.
-
-			// In this case we just clamp to 0
-			return Math.Max(0, (channel - (1 - alpha)) / alpha);
-		}
-	}
-}

Xamarin.Forms.Platform.iOS/Renderers/SafeShellNavBarAppearanceTracker.cs

@@ -38,7 +38,7 @@ namespace Xamarin.Forms.Platform.iOS
 			}
 
 			if (!background.IsDefault)
-				navBar.BarTintColor = BarAppearanceTrackerUtils.UnblendColor(background).ToUIColor();
+				navBar.BarTintColor = background.ToUIColor();
 			if (!foreground.IsDefault)
 				navBar.TintColor = foreground.ToUIColor();
 			if (!titleColor.IsDefault)

Xamarin.Forms.Platform.iOS/Renderers/SafeShellTabBarAppearanceTracker.cs

@@ -34,7 +34,7 @@ namespace Xamarin.Forms.Platform.iOS
 			}
 
 			if (!background.IsDefault)
-				tabBar.BarTintColor = BarAppearanceTrackerUtils.UnblendColor(background).ToUIColor();
+				tabBar.BarTintColor = background.ToUIColor();
 			if (!foreground.IsDefault)
 				tabBar.TintColor = foreground.ToUIColor();
 			if (!unselectedColor.IsDefault)

Xamarin.Forms.Platform.iOS/Renderers/ShellSectionRootHeader.cs

@@ -30,7 +30,7 @@ namespace Xamarin.Forms.Platform.iOS
 
 		protected virtual void SetAppearance(ShellAppearance appearance)
 		{
-			SetValues(appearance.BackgroundColor.IsDefault ? _defaultBackgroundColor : BarAppearanceTrackerUtils.UnblendColor(appearance.BackgroundColor),
+			SetValues(appearance.BackgroundColor.IsDefault ? _defaultBackgroundColor : appearance.BackgroundColor,
 				appearance.ForegroundColor.IsDefault ? _defaultForegroundColor : appearance.ForegroundColor,
 				appearance.UnselectedColor.IsDefault ? _defaultUnselectedColor : appearance.UnselectedColor);
 		}

Xamarin.Forms.Platform.iOS/Xamarin.Forms.Platform.iOS.csproj

@@ -157,7 +157,6 @@
     <Compile Include="Forms.cs" />
     <Compile Include="PageExtensions.cs" />
     <Compile Include="Renderers\WkWebViewRenderer.cs" />
-    <Compile Include="Renderers\BarAppearanceTrackerUtils.cs" />
     <Compile Include="Renderers\ElementSelectedEventArgs.cs" />
     <Compile Include="Renderers\IShellContext.cs" />
     <Compile Include="Renderers\IShellFlyoutContentRenderer.cs" />

Xamarin.Forms.Xaml.UnitTests/Issues/Gh4102.xaml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ContentPage
+		xmlns="http://xamarin.com/schemas/2014/forms"
+		xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+		xmlns:local="using:Xamarin.Forms.Xaml.UnitTests"
+		x:Class="Xamarin.Forms.Xaml.UnitTests.Gh4102"
+		x:DataType="local:Gh4102VM">
+	<Label x:Name="label" Text="{Binding SomeNullValue.SomeProperty}"/>
+</ContentPage>

Xamarin.Forms.Xaml.UnitTests/Issues/Gh4102.xaml.cs

@@ -0,0 +1,38 @@
+using System;
+using System.Collections.Generic;
+using NUnit.Framework;
+using Xamarin.Forms;
+using Xamarin.Forms.Core.UnitTests;
+
+namespace Xamarin.Forms.Xaml.UnitTests
+{
+	public class Gh4102VM
+	{
+		public Gh4102VM SomeNullValue { get; set; }
+		public string SomeProperty { get; set; } = "Foo";
+	}
+
+	public partial class Gh4102 : ContentPage
+	{
+		public Gh4102() => InitializeComponent();
+
+		public Gh4102(bool useCompiledXaml)
+		{
+			//this stub will be replaced at compile time
+		}
+
+		[TestFixture]
+		class Tests
+		{
+			[SetUp] public void Setup() => Device.PlatformServices = new MockPlatformServices();
+			[TearDown] public void TearDown() => Device.PlatformServices = null;
+
+			[TestCase(true), TestCase(false)]
+			public void CompiledBindingsNullInPath(bool useCompiledXaml)
+			{
+				var layout = new Gh4102(useCompiledXaml) { BindingContext = new Gh4102VM() };
+				Assert.That(layout.label.Text, Is.EqualTo(null));
+			}
+		}
+	}
+}

Xamarin.Forms.Xaml.UnitTests/Issues/Gh4103.xaml.cs

@@ -10,14 +10,10 @@ namespace Xamarin.Forms.Xaml.UnitTests
 	{
 		public string SomeNullableValue { get; set; } = "initial";
 	}
+
 	public partial class Gh4103 : ContentPage
 	{
-		private string _someNullableValue = "initial";
-
-		public Gh4103()
-		{
-			InitializeComponent();
-		}
+		public Gh4103() => InitializeComponent();
 
 		public Gh4103(bool useCompiledXaml)
 		{