From 368a375f13fc2e4b5ff00dbbdd7a2d6bb53988eb Mon Sep 17 00:00:00 2001
From: Paul DiPietro <pauldipietro@users.noreply.github.com>
Date: Mon, 12 Sep 2016 06:51:19 -0500
Subject: [PATCH] [C] Prevent enabling a Button via setting a Command (#308)

---
 .../Bugzilla43354.cs                          | 56 +++++++++++++++++++
 ...rin.Forms.Controls.Issues.Shared.projitems |  1 +
 Xamarin.Forms.Core/Button.cs                  |  4 +-
 3 files changed, 58 insertions(+), 3 deletions(-)
 create mode 100644 Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla43354.cs

diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla43354.cs b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla43354.cs
new file mode 100644
index 000000000..6ed77b961
--- /dev/null
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla43354.cs
@@ -0,0 +1,56 @@
+using System;
+
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+
+#if UITEST
+using Xamarin.UITest;
+using NUnit.Framework;
+#endif
+
+namespace Xamarin.Forms.Controls.Issues
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Bugzilla, 43354, "Button command being set after IsEnabled enables the button", PlatformAffected.All)]
+	public class Bugzilla43354 : TestContentPage
+	{
+		protected override void Init()
+		{
+			var buttonIsEnabledSetFirst = new Button
+			{
+				Text = "Click to display an alert",
+				IsEnabled = false,
+				Command = new Command(() => DisplayAlert("Test", "Message", "Cancel")),
+			};
+
+			var buttonIsEnabledSetSecond = new Button
+			{
+				Text = "Click to enable/disable button",
+				Command = new Command(() =>
+				{
+					if (buttonIsEnabledSetFirst.IsEnabled)
+						buttonIsEnabledSetFirst.IsEnabled = false;
+					else
+						buttonIsEnabledSetFirst.IsEnabled = true;
+				})
+			};
+
+			var buttonSetCommandToNull = new Button
+			{
+				Text = "Click to set first button's command to null",
+				Command = new Command(() => buttonIsEnabledSetFirst.Command = null)
+			};
+
+			Content = Content = new StackLayout
+			{
+				VerticalOptions = LayoutOptions.Center,
+				Children =
+				{
+						buttonIsEnabledSetFirst,
+						buttonIsEnabledSetSecond,
+						buttonSetCommandToNull
+				}
+			};
+		}
+	}
+}
diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
index adf173df4..1e0a2732e 100644
--- a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
@@ -124,6 +124,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla42364.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla42519.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla43516.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Bugzilla43354.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)CarouselAsync.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla34561.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla34727.cs" />
diff --git a/Xamarin.Forms.Core/Button.cs b/Xamarin.Forms.Core/Button.cs
index 315730760..a4dffc781 100644
--- a/Xamarin.Forms.Core/Button.cs
+++ b/Xamarin.Forms.Core/Button.cs
@@ -180,7 +180,7 @@ namespace Xamarin.Forms
 		void CommandCanExecuteChanged(object sender, EventArgs eventArgs)
 		{
 			ICommand cmd = Command;
-			if (cmd != null)
+			if (cmd != null && IsEnabled)
 				IsEnabledCore = cmd.CanExecute(CommandParameter);
 		}
 
@@ -225,8 +225,6 @@ namespace Xamarin.Forms
 				Command.CanExecuteChanged += CommandCanExecuteChanged;
 				CommandCanExecuteChanged(this, EventArgs.Empty);
 			}
-			else
-				IsEnabledCore = true;
 		}
 
 		void OnSourceChanged(object sender, EventArgs eventArgs)